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Putting 1-ton gear in a 1991 K5

The Butcher

The Butcher

1/2 ton status
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Texas. In a van, down by the river!
Hi everyone. I'm new here, but this site seems like a great place to get some info. I have a whole slew of questions, so any help you guys can give would be greatly appreciated. Let me give you some background info:

I recently purchased a 1991 K5 (stock 350, 700R4, NP241, 10 bolts) and a 1981 Chevy Dually 4x4 (454 w/mild RV cam, Dana 60 DRW front, Dana 70 DRW rear, NP205, SM465). The dually is the donor truck for the swap I want to do.

Here is what I plan on doing. I want to take the 454, the axles, and the transer case out of the dually and put them under the Blazer. The Blazer has a 3-inch body lift, and I am going to add another 8 inches of suspension lift so that I can run 38.5/15-16 Boggers on 16x12 wheels. I have found a manufacturer (from this website actually) that makes the front hubs for the Dana 60 so I can convert it from DRW to SRW for about $375. That takes care of the front. For the back, a friend of a friend is willing to trade me a SRW Dana 70 for my DRW Dana 70 as an even swap. Here are a few of my questions (I'll have several more later, but this gets the ball rolling).

  1. I originally wanted to use a Corp 14 for the rear, but the swap for the Dana 70 as an even trade sounds alot better than paying for a 14-bolt. Would most here agree that the SRW Dana 70 is just as good to use in this swap as a 14-bolt would be?
  2. What kind of issues am I going to face with swapping the 454 for the 350? Ie, engine mounts, a larger radiator, adapter from engine to trans, etc.
  3. Eventually I would like to get a beefier transmission, but for just general street use for awhile, will the 700R4 hold up to the 454 and 38s? The potential exists that I'll just swap the axles first and leave the transmission/transfer case/engine swap for later.
  4. Does a NP 205 mount up directly to a 700R4, or do you need an adapter? If so, any suggestions as to where to get one?

Also, I'm putting an 8 inch lift on this, so I assume I will either need a new driveshaft or lengthen the one I have. What type of mods will be needed to attach it to the Dana 70 instead of a 10 bolt? How about for the front driveshaft to the Dana 60?

These are just the questions off the top of my head, but I'm sure I'll have several more later. I want to say thank you in advance for any help you guys can give me. Glad to be a new part of your community.

The Butcher
 
Bunch of other problems to resolve as you know, but TBI is going to be an issue unless you plan on going carbed (yuck) and unless you DO plan on going carbed, you will have to retrofit an older speedometer cluster into your '91 to keep the TBI happy.
 
I plan on going carbed for now, then fuel injected later. I'm considering keeping the stock engine, etc, and just doing the axles first. This would obviously be the easiest and quickest to get me up and running. Then I could still play with my toy while taking the engine apart and rebuilding it along with the transfer case and possibly the transmission (unless I just buy a different tranny, in which case, does anyone have a good suggestion of which to get?)

One other question I have is about cross-over steering. I've heard of it, and I know it is usually preferable to a steering-arm/block/drag-link correction, but I really have no idea how it works. Anyone know of any good articles on doing cross-over steering to accomodate the 8-inch lift? Thanks.
 
You can convert your front D60 to SRW for about $250 by buying new bearing hub/rotor assemblies thru www.GMPartsDirect.com. (they're about $114 + freight each). I've looked but I can't find the part number right now.

There is an article in the "Technical" section (accessible thru the drop down menu at the top right) about doing crossover. Between that article and ORD's catalog page you should get a good idea of the how's and why's of crossover.

I'm all about the 454 swap but I highly recommend waiting until you can do the swap and keep the TBI. The benefits of fuel injection speak for themselves. :deal:
 
11 inch lift for 38s..... Yikes, that will be quite tall.

What do you plan to do with this truck?
(mall poser/show and shine <---> wheelin/rockcrawler)
 
I can't help with the engine much if you are dead set on eventually running a Rat motor. BUT, far as I know with the right ECM, throttle body, and other goodies is should work. If it was me I would run the stock engine/tranny/and tcase for now and like you mention, just swap the axles and do the lift.

1.THe SRW D70 is a fine unit. It is nearly identical to the 14BFF, but some say the 70 is slightly stouter. Gearing is much more available for it too with tons of aftermarket differentials, unlike the 14BFF. You will need to move each spring perch out one inch and reverse the shock mounts. It should bolt in at this point. Brake lines will fit right up.

2. I am not a fan of the 205 case unless it is absolutely neccessary, which in most cases, it isn't. If you play on rocks then I would go with a 205, otherwise the 241 is an EXCELLENT case and you won't have any problems with it. Infact, I think it's a better case. Shift on the fly and a much better low range.

3. The stock 700R4 tranny will be fine for now if it's in good shape, with the stock engine of course. I don't know what gearing is in your 1 ton but it needs to be at least 4.56. If it has 4.10's thats a little high for 38's. That more than anything (besides a monster Rat) will kill the transmission.

4.The 60 will bolt in outside of needing the spring plates and ubolts off the dually. I would go with crossover like mentioned, I'm sure someone has a link for you like you asked explaining how it works.

5.Driveshafts, you'll need some big ones. :D Get a new shaft made for the rear, a dual cardin (CV) will be needed for the top at the tcase. A 1350 should be ok at the rear end(which is what is stock IIRC) but going to a 1410 would help angle and strength.
The front is another issue, the stocker may still work because the pinion sits back further with a 60 than the stock 10B, but for strength I would have a new shaft built with 1350's.

5. Boggers! Make sure thats what you want because you will kick yourself after you buy them, as soon as they cup on the road.
 
Sweet. Thanks for all the help so far guys.

2Dogs, I plan on building a truck that has the ability to get the crap beaten out of it, but I honestly probably won't abuse it very often. I know 11 inches is pretty tall, but 38s on a 12 inch wide wheel will need that much lift (especially if I want blocky-ass boggers) unless I plan on some seriours wheel-well mods. I have a buddy that owns a body shop, so that's not out of the question, but this truck is in GREAT shape and I don't really want to chop it up too much. Likewise, that is probably why it won't see too much off-road abuse. There are no dents on this thing (even door dings!!!) other than one small crease on the back tailgate and it is actually in the aluminum trim plate that goes across the outside of the back tail-gate.

Again, thanks for all the suggestions so far. Keep 'em coming. As I process all the info you guys throw my way I'll be able to better narrow down what route I will go.

Rjfguitar, I've always read the 205 is a great idea b/c it is so bullet-proof. I have one (in the dually) so I thought I would use it. If you think the 241 is fine (especially since this thing will not see constant abuse) then that would be great b/c as I said, I'd like to be driving this thing sooner rather than later and it would be easier/cheaper/faster to just do the axles and wait on the engine/trans etc.

The 60 has 4.56s and the guy was going to open the 70 sometime today or tomorrow and see what it has in it. If it has 4.10s, I was going to go ahead and order 4.88s for the rear and not hook up the front drive shaft until I got the cash together to get the 4.88s and a locker for the 60. Any suggestions for lockers for the 70? I assume a Detroit would be the preference, but any others (especially something that might prove more street-able but still good off-road) would be appreciated.

Do you know of anyplace that has spring-perches and shock mounts that I could use to re-attach to the 70 once I cut off the factory ones, or can I re-use the factory ones? I assume they will need to be cut off, thus making them unusable, but if that is not the case please let me know. Thanks.

Oh, and I plan on Boggers in no small part b/c I love the way they look. This truck will be driven mostly as a toy on the weekends (admittedly mostly on the street) and will probably see very minimal highway time. The other thought I had was to go with a 38x15.50 R 18 Toyo Mud, but the price difference was obscene. 38 inch SSRs were another option, but I just really like the look of the bogger. I know they ride like crap, are noisy as hell, and cup like a mofo. But, no other tire looks that gnarly!!! I suppose I would be open to anyone else's suggestions for a wide (14 inch or more) 38 inch tall tire for this truck. So, let me know your favorites.

Nverenuf, thanks for the info on the hub assembly and the cross-over info. Last I heard the hub assemblies from GM were going for something like $1000.00 but if you say they are much cheaper, I'll definitely go that route. The company I found in Austin, Tx will probably be about the same price that you quoted, but buying from GM parts would be preferable in case of quality issues.

Thanks again guys. It's all very much appreciated.
 
Ah... I found the number!

Part #15635530
Current price = $114.72 + freight.

I know a guy that has ordered these and the total was +/- $140 each to his door. Much better than $375 :cool1:


On the subject of the 205, since the dually has a 4spd the 205 will have a 10 spline input. Your 700R4 will have a 27 spline tailshaft so to put the two together you'll need a TH350/205 adapter + 1" spacer for the tranny side + a 27 spline input shaft for the 205. I'm a 205 fan but this is probably a project to put off until a later date.

Be sure to order the D70 parts for the actual axle you're going to use as some of the parts will be different between the SRW and DRW versions.
 
Thanks for the part number. As you said $280 + freight is a hell of alot better than $375 + freight!

I assume the SRW 70 will have the same internals, etc as all SRW 70s regardless of the truck they came out of. Is this a correct assumption, or do I need to rack the brain of the guy with the SRW 70 to see if he can figure out where in the hell it came from to begin with?

Yeah, the more I think about it the more I think I'm going to start with the axles and then do the rest of the swap later. That will give me more time to tear down the engine and transfer case (and more time to get more $ together to spice up the engine if I so choose). Since I will probably do that swap later, what suggestion do you guys have for a stouter (is that a word?) transmission? TH400, or perhaps the 4L80E? What are the swap adapters required between all of these components, and which of the two trannies would be the easiest to come by?

Nvrenuf, if I did stick with the 700R4 where can I get the adapters you mentioned? I assume someplace like Advanced Adapters, but anyone else have a place to look?

Man, I sure am glad I joined this site. I've been asking myself these questions for the last 2 months and haven't gotten very far! :D

The Butcher
 
On the D70 be sure to get a description of the truck it came out of (yr/make/model) and use this for parts. D70's can be very confusing because there are many variations (both SRW & DRW) and it can make a big difference on getting the correct parts.

I would watch the For Sale section here or Ebay (etc) for the parts to convert your 205. The AA stuff is nice but you'll problably spend more than double on there stuff over used items. These types of parts show up here every month or two.
 
4L80E is a good, dependable transmission and with OD, allows you to run some good wheeling gears yet drive it around without the RPM's to the moon.

4L80E requires a computer to run, but that would tie in good with keeping the TBI, since 454/TBI/4L80E/241 was a stock application. If it's possible to mate a 241 case to a 4L80E, (I suspect it was factory in some apps) then your transmission/transfercase/speedometer/PCM issues would be solved all at the same time.

TH400 is an "easy" way to get strength, but if you've got the time, inclination, and money, the 4L80E would be more rewarding in the end, for most people.
 
The 4L80E/241 combo was a factory offering in a Sub, I believe Mini_Mull has this set up.

Trivia - TransGo offers parts to run a 4L80E without a computer. :cool1:
 
Thanks for the tranny/transfer case info. I like the 454/4L80E/241 idea. Anybody know what year subs came with the 4L80E/241 combo? Wouldn't late 80's-early 90's 3/4-ton pickups probably have had this as well?

Forgive my ignorance, but will the TBI from the 350 mate up to the 454? The 454 has a Holly 650 (I think, but it could be an 800). What all is involved in going from carbed to TBI?


The Butcher
 
The 4L80E was introduced in '91 so that's your only year to look for (for either a 241 or 205 combo). Either combo would have come as a 32 spine set up so there will still be some converting to be done on your t-case.

The 4L80E/241 could have also come in the newer body style 88+ C/K series trucks but the transfer case will have the front output on the left side.
 
Rjfguitar, I've always read the 205 is a great idea b/c it is so bullet-proof. I have one (in the dually) so I thought I would use it. If you think the 241 is fine (especially since this thing will not see constant abuse) then that would be great b/c as I said, I'd like to be driving this thing sooner rather than later and it would be easier/cheaper/faster to just do the axles and wait on the engine/trans etc.

The 60 has 4.56s and the guy was going to open the 70 sometime today or tomorrow and see what it has in it. If it has 4.10s, I was going to go ahead and order 4.88s for the rear and not hook up the front drive shaft until I got the cash together to get the 4.88s and a locker for the 60. Any suggestions for lockers for the 70? I assume a Detroit would be the preference, but any others (especially something that might prove more street-able but still good off-road) would be appreciated.

Do you know of anyplace that has spring-perches and shock mounts that I could use to re-attach to the 70 once I cut off the factory ones, or can I re-use the factory ones? I assume they will need to be cut off, thus making them unusable, but if that is not the case please let me know. Thanks.

Oh, and I plan on Boggers in no small part b/c I love the way they look. This truck will be driven mostly as a toy on the weekends (admittedly mostly on the street) and will probably see very minimal highway time. The other thought I had was to go with a 38x15.50 R 18 Toyo Mud, but the price difference was obscene. 38 inch SSRs were another option, but I just really like the look of the bogger. I know they ride like crap, are noisy as hell, and cup like a mofo. But, no other tire looks that gnarly!!! I suppose I would be open to anyone else's suggestions for a wide (14 inch or more) 38 inch tall tire for this truck. So, let me know your favorites.
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Sounds good to me. I agree, Boggers are just insane looking. Plus, they provide INCREDIBLE traction. You sound like you have the same plans for your truck as I do for mine. I run 35x16 boggers on 16.5x14 Welds, look great. If you have another vehicle than it's a lot of fun having a nice lifted truck on Boggers or whatever. The sound they make and the way they look are a lot of fun on the weekends. With that few amount of miles, their longevity doesn't matter much, they'll last a long time. I plan on Boggers again after my current set are shot. I do wheel quite often though too.

I would suggest the 18x15.50 Parlini Jones tire, they last a LONG time.

Go with 5.13's. You'll have 38's.

The 241 is plenty strong for your plans. Trying to actually find someone that has broken a 208 or 241 from wheeling is very hard. Most of their problems are from high mileage worn out cases and the aluminum cracking because of banging them against rocks. I run a 241 behind a built 406ci/built 700R4 down to 4.10's and 35x16 boggers. I love it. I don't want a big heavy 205 that has a crappy low range and is a PITA to get to work with a 700....
 
rjfguitar- Yeah, everyone tries to dissuade me from going with the Boggers, but since it is a second vehicle I'll put up with their negatives (ride like crap, wear out fast) in order to get what I see as their positives (looks, sound, pure intimidation factor). I like the Parnelli Jones Dirt Grips, but they are WAY too expensive IMO. I can get the Boggers for about 2/3 the cost. Obviously we are talking about bias vs radial, but again, for a second vehicle I'd rather get the cool looking tire for cheaper.

Do you really think 5.13s are the way to go? I could see how they would be with the 350 in it, but once i put the 454 in (assuming i end up doing so), wouldn't you think the 4.88s would be better. I guess with the od in the 700R4 the 5.13s wouldn't be too out of this world with either engine. I'm just afraid of what my RPMs would be if I did decide to try and take this thing on the highway once in awhile. Anyone know what the switch over point is in the D60 and the D70 as far as carriers go? I assume 4.56 and up has the same carrier, and 4.10 and down have a different carrier.

One other thing, this truck has about 175,000 miles on it. It was obviously primarily a street driven truck, and other than a massive power-steering leak, and an oil drip that I can't seem to locate the source of, this thing is in great shape. Even the case on the 241 looks clean (so either it has been worked on and cleaned at that time, or someone got under there and cleaned it prior to selling it). The 700R4 seems to work pretty well (no major clunks, bangs, or slips), but I hear everyone talk about building theirs up. What all needs to be done to build up a 700R4?

The Butcher
 
You don't need 11" of lift to clear 38's. I ran 38"s for a couple years with 5.5" BDS springs on the dana 60 up front and 9" of lift in the back.

I am running 42"s now with the same lift. However, I will need to trim the front fenders just a little more...

dsc0136015is.jpg


dsc0138519ft.jpg
 
You don't need 11" of lift to clear 38's. I ran 38"s for a couple years with 5.5" BDS springs on the dana 60 up front and 9" of lift in the back.
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He needs at least 11" of lift because he doesn't want to chop fenders. Also he wants it to look good.
 
Well, when you factor in that the Parnelli's will last twice as long they are not so expensive. Not to mention boggers should be balanced a few time through their live's as the rubber wears off.

5.13's are the way to go no questions asked. Most people consider 5.13's the best for anything 35" and up. If you look at a gear chart 5.13's don't bring the RPM's up much from 4.88's anyway.
 
rjfguitar said:
Well, when you factor in that the Parnelli's will last twice as long they are not so expensive. Not to mention boggers should be balanced a few time through their live's as the rubber wears off.

5.13's are the way to go no questions asked. Most people consider 5.13's the best for anything 35" and up. If you look at a gear chart 5.13's don't bring the RPM's up much from 4.88's anyway.
Click to expand...

Well, 5.13s it is. Guess you are also right about how long the two tires will last, and the cost difference isn't so bad.

BDS springs seem to be all the rage here. I'll probably get flamed for this, but I was just going to use a Skyjacker 8" kit (springs all the way around) plus my 3" bodylift to clear the tires. I also looked at the articles on here about using the longer springs up front and moving the shackle. Looks like a good idea but in all honesty that might be a little more than I want to mess with right now. What's the deal with BDS springs? I've heard of them before but not sure where to get them, or why they are so popular. Any help in that area would be appreciated.

Can anyone address my TBI questions about going from the 350 TBI to the 454 (carbed)? Essentially what all is involved in going to TBI on the 454 with what I have now from the 350? Thanks.

The Butcher
 
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