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Mixed info on 203/205 swap driveshaft ?'s

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DizturbedOne

1/2 ton status
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It's a 77 GMC Jimmy with 400SBC/TH350/NP203 w/5" lift and 35's. There's no body lift. The 203 is limping around in Lo-Lock right now so I'm going to the 205. I got a 205 and adapter for my TH350 off a 73 K20 pickup yesterday, and now I'm searching for the driveshafts but I'm reading EVERYTHING from "use what you have now it'll probably work" to "find a truck with a 350/205 and get the driveshafts" to "you have to have it custom made no matter what". I've been reading and searching for hours on end just to get more conflicted as time goes by. I want to at LEAST get a rear shaft for it and get my truck driving on a good t-case in the next day or two (it's my only DD because the wife is driving the Camaro to work) then I have about a week before my next wheeling trip to get a front shaft in.

Any thoughts or suggestions? A general consensus of what seems to work best most of the time would be good. Comments from guys with lifts and setups close to mine would be great. Anybody know exactly how much of a difference I'm trying to make up here? That seems like a very basic question I can't find the answer to. Any help I get is much appreciated guys.
 
I had an Turbo 350/NP203 in my K5 with a 4" lift. I swapped an SM465 with an NP205 out of a 77' 3/4 ton 4X4. I had to lengthen my driveshaft about 6", and get a conversion U-joint Spicer #5-460X, from 1310 on the driveshaft to 1350 on the transfercase. It all cost about $140~ The front driveshaft was different, I used the shaft from the 3/4 ton.Length was the same, how they bolted to the transfercase output was different. Hope this might help.
 
My 76K5, 400sb/th350/np203 stock rear driveshaft was about 36". I swapped in a 27 spline np205, about 6" of lift, and a 14bff rear and my rear 1350 shaft is about 46". I'd guess you're going to have to make up 8-10". The np205 you picked up at the junkyard should be a 1310 output just like your 203 was.
 
Thanks you guys. Anyone else that can chime in, I'm sure all of it would help me sort this out a little in my head for the next day or two before I tackle it. It's all very appreciated.

Chalet, I'm pretty sure you're right about them both being 1310 yokes but truthfully I'd have to look at my own truck to make sure, lol! Gimme a break though, I've only had it a week!

Today a guy I know that still works at a shop I worked at a couple years back, said he can get me a deal on the drivelines to shorten one and lengthen the other for about 100 bucks. So I may go that route just for ease of the project. I doubt I'll find a 4"-6" lifted K5 truck with a 350/205 combo just sitting around the junkyard with both drivelines in it so it sounds the most feasible... But I'll still try once more while looking for some other stuff at a different wreckers anyways (a York compressor, e-brake bracket, the bolt I lost for my TH350 adapter, misc. interior knick knacks).
 
A 205 t-case is much shorter than a 203 so YOU WILL need a new rear shaft or at the least have a driveline shop lengthen your existing shaft. The front shaft will not bolt to the yoke on the 205 and there isn't a yoke available that i'm aware of that would allow it.
 
4X4HIGH said:
A 205 t-case is much shorter than a 203 so YOU WILL need a new rear shaft or at the least have a driveline shop lengthen your existing shaft. The front shaft will not bolt to the yoke on the 205 and there isn't a yoke available that i'm aware of that would allow it.
Click to expand...

THANK YOU 4X4

This is exactly what I was looking for.

So at the least, I still need to find a front shaft, and have the rear one fabbed... Anyone know some good running gear combos/trucks to look under for an appropriate front shaft? Think it's feasible to find a front shaft that will bolt in without mods?
 
The front shaft will need to come from any truck with the TH350/205 combo. The axle end is the same no matter what axle is in the truck. You might get lucky and find a stock shaft that will work with the 5" lift you have (my front shaft is still stock and i have 6" although i am running a D60 up front and IIRC the pinion area of the axle is longer so that makes up for some lift).

Do you know what kind of Yoke or flange is on the 205.
 
It's a bolt on yoke for both sides on the 205. I know the front shaft on my 203 has a bolt on yoke, and the slip is in the middle of the driveshaft itself, but I can't recall the back for sure.
 
IIRC ALL 203's use a driveshaft with a yoke that uses 4 bolts from the back side of the yoke on the 203.
 
So you're saying it wont be the same as the u bolt configuration on the 205 I just pulled?

Great convo so far, I got alot to look for tommorow
 
Finding the appropriate 205 front shaft is pretty hard to do. I used a shaft from a newer truck and had it shortened to work on my 205. IIRC they had to cut around 6" out of the shaft to get it to match the stock shaft.

Are you saying the front shaft output on the 205 you just pulled uses a u-joint, not a CV flange? If so, is it the same setup as your original 203 shaft? If it is, you should be able to just shorten the shaft to the appropriate dimensions. The added advantage is that with 6" of lift you can have the shaft shortened just enough to work ideally for your lift.
 
DizturbedOne said:
So you're saying it wont be the same as the u bolt configuration on the 205 I just pulled?

Great convo so far, I got alot to look for tommorow
Click to expand...

I've got 2 205's from behind th350's here. One's a fixed, 1310, u-bolt style yoke rear output(was anyway) and fixed, 1310 u-bolt sized yoke front output.

2nd one is a later model, slip yoke rear out put and flat, flanged 1310 front output.

If yours is like the 1st with a 1310 yoke, you should be able to use your old driveshaft and have it lengthened.

$100 sounds reasonable to me.
 
Here is a pick of the 203 and driveshaft that came out of my 73 K5, and a pick of the 205 and driveshaft out of a 77 3/4. hope it helps

203.jpg

2032.jpg

xxxxxxx.jpg
 
From the op...

got a 205 and adapter for my TH350 off a 73 K20 pickup yesterday
Click to expand...

did they put th350's in 3/4 tons? Either the make of the donor truck is wrong, or he's got a 205/adapter for a th400, or I'm wrong.:crazy:
 
chalet2506 said:
From the op...



did they put th350's in 3/4 tons? Either the make of the donor truck is wrong, or he's got a 205/adapter for a th400, or I'm wrong.:crazy:
Click to expand...

Just because he pulled it out of a 73 K20 doesn't mean it was original in that truck. People have been swapping parts for years and who knows what's original anymore.

To the OP, the last pic is a perfect example of what i was talking about. The shaft from the 203 will not work with a 205 and the Yoke cannot be swapped either IIRC. I can't recall what the spline count on a 203 front output is but the early 205's were 10 spline and used a Yoke and the newer ones were 30 spline and used a flange.
 
Yes, the front of the 205 is a flange type for a CV end on the axle, sorry about the confusion. I can get that shaft from the donor easily. Maybe I should just grab the rear as well? How likely is it for a rear shaft from a longbed pickup to be long enough to mod without having to add material? That would be the cheapest route for me, taking it down to about 70 bucks for both shafts to be made if I didn't have to put a new tube on one.

I'm sure it was a TH350 though. The adapter is a female to female also, isn't that a TH350 only thing? It is a 73 either way, alot of stuff can happen over the years. The fact mine had a CV style shaft on it seems to imply it was a newer T-case that was swapped into the truck anyways.

I can get the front shaft from the truck I pulled the 205 from, so I'll go that route. I'm pretty sure the rear was damaged from the forklift they were moving cars with though. Worse to worse I'll grab it just to have the yokes on both sides and have them make a tube for it. If not, there's another pickup truck with a 205 out there that I'll dig under.

Thanks for all the help guys, this thread has done so much for me in terms of getting me info + just straightening my own thoughts out on the subject. Good stuff! :bow:
 
The longbed shaft will be a 2 peice with a carrier bearing. Just have them lengthen your rear shaft, and change the end to match your 205, I would think that would be easier?
 
Alright, now I'm on the HUNT! Since my Jimmy isn't a stock size and won't accept any form of stock shaft anyone can think of... I'm going to find some shafts at a junkyard (they cost almost nothing) that have the correct yokes already so I can have them just put new tubes on the shafts for the length I need. Awesome thread guys, thanks for all your help in this matter!

I hope this thread helps out someones search in the future
 
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