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Parts Interchangability

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nomad350z

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I've recently come into ownership of an '83 K5 Blazer, and am trying to figure out what path I wish to take wtih the truck.

Currently it has a lo-po 305, TH350 combo and the original transfer case. If I'm to keep it a gasoline motor, can I use a 700R4 withe the NP208 transfer case? I realize the 700R4 is electronically controlled, but there is a kit on summit to override that....

Also, I have a GMC pickup (late 80's, maybe early 90s) with a 6.2 turbodiesel and a standard transmission (I believe its a 4 speed with an ultra-low stump pulling 1st gear). I've dabbled with the thought of swapping this in for the blazer's 305, but was wondering if it would bolt up to the NP208.

Its going to be a daily-driver/weekend warrior build, so nothing too crazy (or expensive). Will either of these setups work?

Thanks guys.

The Newb, fresh in from thirdgen.org
 
Yes you can use a 208 with a 700r4. You might even be able to get away with the adapter you have now (if you have a 208 currently). If not, 700r4/208 is a very common combo.

I'm not up to speed on the turbo diesel motors, so I have no idea what transmission would be behind it.
 
thanks for the info on the 700r4, but I'm still curious about this diesel setup. The torque, efficiency and ability to run biofuel has me intrigued.

Sorry for being so vague, but I don't know the exact year of the C/K pickup wiht the diesel setup. I do know its late 80s, maybe early 90s with two headlights, one on each side. It has a 6.2 turbodiesel and a standard tranny, RWD only (no 4x4). The transmission has 5 forward gears, but the 'first' gear is an ultra-low ratio for hard work, like pulling tree stumps or getting a large payload moving from a stop. Without that ultra low ratio, its basically a 3 speed wiht overdrive (4 gears).

Shift Pattern:

Ultra Low---------2nd------------Overdrive
---|-----------------|-----------------|
---_____________|____________|
---|-----------------|-----------------|
1st----------------3rd-------------Reverse

(Ignore the dashed lines, they're only there to keep space between the gears while posting, otherwise it would be a jumbled together. Focus on the Solid lines)

Basically its a standard 5-speed shift pattern.



Anybody know what this tranny is? How about if it'll bolt up to an NP208?
 
Cool on having an 83 . My first one ( the resto project ) is an 83 . It has the 9.2 to 1 compression 305 ( VIN H ) . The th350 you have was swapped in when the 700r4 died I assume , as that was the case in the early 80's most of the time .

Two headlights on the donor pickup would indicate a work truck front end . Newer body style truck . The diesel will physically fit in the 83's engine bay .

You have to make your own exhaust from the manifolds back , as the newer trucks were laid out to be drivers side transfercase ( if 4wd ) and the 2wd drive exhaust would follow suit and be in the way with your passenger drop transfercase .

The 2wd stick tranny will not fit a transfercase unless that trans had an adapter and tailshaft available for 4wd versions .

Personally I would do the 700r4 tranny , they were installed behind diesels , and 88-91 were the best years . Not electronic . Just electrically locked up torque converter . And diesels have their own specific stall speed torque converter so you need that too .

You can always hook the current tranny and case up to the diesel since the bellhousing pattern is the same , but more gears the merrier :)
 
Thank you pauly383! I'll keep you informed as the build progresses.

Your truck looks like mine, white and all. Besides the motor, I'm looking forward to getting 4" suspension lift and some 35"s. I know the tires might be a bit big for the application, but they look too damn good. :D
 
just a thought

i would keep a manual behind the 6.2 as these made them more responsive.

to do so you could see if you salvage yd would trade a sm465 np205 set up, for what you currently have. and throw in a ranger od.

or get an nv4500 adapted to a np205

we had an '84 burb 6.2 with a th400, destroyed tranny and flexplate. then put a 700r4 back in and flexplate again self destructed after a while. then sold the burb.

with an auto it was very sluggish, and with 700r4 it did get 20mpg.

the manual was able to harness more of the motors torque, but would have been better with an od.

ps ditch the 305 and that manual tranny is an sm465
 
sorry i missed it. i was half way through a smart aleccy post quoting his first post when i thought i better double check before i get fooled twice and look like a huge idiot.:doah::doah:

so you should have either the nv 4500 or the nv 3500. if it's the nv4500 keep it and change out the rear shaft and adapter for the four wheel drive one.

ps thanks martin
 
Ultra low first gear tells me it's a two wheel drive version of the NV4500. The NV3500 had a regular first gear.

I'd run a divorced 205 behind that. There is no "rear" shaft to swap out. To make that tranny a 4WD version you have to swap the mainshaft and add a 4WD adaptor housing. Your existing NP208 will bolt up, but will need a 32 spline input gear swapped in place of the current 27 spline version.

This pic shows the adaptor housing

DSC00488-1.jpg


The vertical chunk with the gears on it is a partially assembled mainshaft...give you an idea of what's involved with swapping that out.

DSC00240.jpg


Mainshaft installed in tranny...

DSC00512.jpg


The 5 speed is pretty good behind the diesel. Get's more power to the ground, and keeps the freeway rev's down to a good level for fuel economy.

Rene
 
Yup, should fit, but it will be fairly tight.

I don't know if you can do the same on a K5, but a longbed truck you can make your front and rear driveshafts the same length with the 205 so you only have to carry a single spare driveshaft offroad...

I would imagine that the diesel engine is a mechanically injected 6.5L turbo diesel with an NV4500 manual transmission (as surmised above). While running a divorced t-case would be nifty, I'd think it to be easier to swap out the mainshaft on the NV4500 for a 4x4 version and run a 32 spline 6 bolt round married transfer case. Just saves you on having to build crossmembers to mount both the transmission and the divorced case, not to mention the added cost of having three driveshafts built.

Being that your K5 is an 83, GM had already standardized the length of most of it's transmission / transfercase combinations, and should you run a married NV4500 / NP208 or NP241, you would be able to re-use your existing transmission mount & crossmember, along with your driveshafts.

You will also need to retrofit in a hydraulic master cylinder into your K5, which involves removing the steering column to install a set of clutch pedals, installing a stud on the clutch pedal in the correct position, and mounting the 93 master cylinder to your firewall. I did so on my K25 with relative ease.

Three issues that you will run into that are not easily solved involve the external slave cylinder to front driveshaft clearance (you'll be fine with 4" of lift or more), the NV4500 shifter boot to NP208 shifter housing clearance (need a very small boot for the 4500, or to relocate the 208 shifter), and the downpipe to frame rail clearance issue (you'll have to either install a 3" body lift to have enough room to run the exhaust inside the frame rail, or have your exhaust run outside the frame rail, straight piped 6.2 / 6.5L turbo diesels sound similar to a BBC with very raspy mufflers)

Other swap considerations include swapping out for hydroboost brakes, mounting the huge 6.2L diesel radiator, the engine oil cooler (6.5L stuff won't fit our trucks, I tried, wound up with a B&M plate cooler), and the fuel system. The 6.5L will utilize and electric lift pump that your K5 does not have, and picks the fuel up on the driver's side frame rail stock. The injection pump should have between 8 - 9 PSI on it (but can live it up to 15 - 18 before the IP's timing starts to get thrown outta whack), and should not drop below 2 PSI at wide open throttle. You can use the stock 6.5L inline electric fuel pump if you use some Swagelok or equivelent compression style fittings to patch it into your hard supply line. You want to have the pump as close to the tank as possible while still being as far below the tank as possible.

Use the factory 6.5L fuel filter assembly, and simply pick the fuel up and return on the passenger side by bending up new hard lines where possible. Use as few fittings or soft hoses as you possibly can, as they are all potential leak points. A diesel fuel injection system that leaks, or allows air in can cause some majorly annoying starting issues, and a significant lack of power.
 
wow I just got hit with a ton of info. Remember, I'm still a little new to this.

Thank you all for all your input! Russell, sounds like you've done this before...

So, if I swap out the 2wd mainshaft for the 32 spline 4x4 one, the tranny and transfer case will bolt right up? If not, where can I get an adapter?
 
Last edited:
Yep, you'll need to get a 4x4 5th gear housing somewhere, as your 2wd housing does not have the mounting face for the transfer case. Once you've bolted that 5th gear housing on, any 32 spline 6 bolt round pattern transfercase will bolt straight on.

To change out the mainshaft, you will need access to some hefty bearing seperators / pullers, and a press. There is a special tool required to remove / install the 5th gear retention nut as well. I was able to do an NV4500 overhaul in my shop without too much trouble.

If you PM me your email address, I can send you an overhaul manual
 
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