NP205 Swap

[Mastiff]

CUCV's that use the NP205 (like the M1031) use the long input in a figure 8 NP205. They use the same 2.375" output TH400 as the TH400/NP208 and the same adapter as the civilian mid 85 and older TH400/NP205's.

So the whole case is unique? 35 spline long input was never produced in fig-8 otherwise, I thought. And sweetk30 says the input shafts won't just drop in to the old cases...

EDIT: Did some surfing. Looks like a figure 8 with 32 splines (not 10 at least). Does have a slip yoke. And PTO.

 

[Hogback Fabrication]

To use your TH400 as is, you need a TH400/NP205 adapter. As mentioned, there are two versions: 84 and older is the figure 8 pattern on the 205 (that adapter is still available new) and 85-91 uses a round pattern on the face of the 205 (used only, fairly rare).

Both adapters are ~4" long, and either way you need a long 32 spline input gear in your 205. ~90% of passenger drop t-cases you'll find will have the small input bearing (10, 23 or 27 spline) and will need to be machined for the bigger input plus finding the long 32 spline input gear (used only at this point), so you can convert the common 205's over if you can find the gear and have the machine work done.

85-91 GM 205's will have the long 32 spline input gear that you need but they're all round pattern and require the rare, used only adapter.

The CUCV 205 is the only figure 8 case that ever had a long 32 spline input, but they are one of the rarest 205's. If you can find one, you'd just need the TH400/fig 8 adapter that's still available new.

 

[sweetk30]

wo wo wo stop .

35 spline is typo by you .

I said 10 AND 27 spline case if you wana swap in the larger 32 spline input needs the case machined for the bigger input bearing .

the inputs can swap long or short 32 spline.

all 205 tcases have a pto port.

and unless the 205 was in the later years of production 80-up had a 2 section drive shaft it got a slip yoke.

the slip yoke is just a simple shaft swap and seal retainer. not hard to fix at all.

 

[82355]

Seems like a lot of hassle for you to downgrade transfer cases.

Martin

 

[sweetk30]

then why do most people want them over those super strong 208 cases ?

its your opinion you like the aluminum stuff.

but I have never seen a broken 205 unless straight up abuse so far past even thinking how to do it its not normal .

 

[82355]

I have never said an NP205 wasn't stronger than an NP208/NP241. That is the only thing better about an NP205, brute strength. Other than that, they have nothing going for them. Heavy, loud, hard to shift, poorly geared. Those aren't positive attributes.

Martin

 

[Mastiff]

Yeah, 35 spline is a typo on my part.

Let me see if I can summarize the options:

1) Find a CUCV 205 and a pre-85 TH400 figure 8 adapter. Problem: Likely impossible to find and $$ if I do.

2) Find round-6 input 205 with long 32 spline input and associated TH400 adapter from 85-91 truck. Crew cab has fixed yoke rear. Problem: Difficult to find case and adapters are $$.

3) Get an old figure 8 case without 32 spline input, and easier to find TH400 figure 8 adapter. Find a used long 32 spline input. Problem: Need to machine case for bigger input, input shafts might be $$.

4) Just pay ORD or someone for a setup ready to bolt in. Problem: $$$$

In options 1-3 there's a high likelihood of the rear output being slip yoke too, so will have to obtain parts for conversion, not sure of $$ impact.

Does that look correct?

 

[sweetk30]

front outputs were never slip yoke.

these 205 tcases are easy to redo . check my 4l80-203-205 write up in tech section .

 

[Mastiff]

front outputs were never slip yoke.

these 205 tcases are easy to redo . check my 4l80-203-205 write up in tech section .

Typo again, corrected in original post.

Yeah, understand it's not hard, but not certain about parts cost. Found one thing on ebay, $85.

http://www.ebay.com/itm/CHEVY-GMC-N...Parts_Accessories&hash=item20d5ef0624&vxp=mtr

 

[sweetk30]

that's it minus what ever flange or yoke you will be using .

 

[Mastiff]

Can you tell what kind this is from this small pic, and the adapter still on?

 

[nvrenuf]

Th350, square 4 bolt pattern on trans side of adapter.

 

[Cucv_M1008]

This thread has given me a lot of info i have been looking for a while ty op.

 

[sweetk30]

yep that one was th350 or if correct parts in the tranny a 700r4.

a th400 adaptor has 6 bolt holes were it bolts to the tranny . and also only the 27 spline th350 or 10 spline 4 speed stuff had a coupler sleave . 32 spline was male/female .

 

[Mastiff]

I think this is the right thing, right? Guy wants $350 though.

 

[JDNobodi]

That is the figure 8 205/th400. It will bolt up, but the transmission tail shaft won't reach the short transfer case input.

 

[JDNobodi]

You could buy it and could swap out the input on the transfer case, let wait to sweet k30 has to say about that option. Edit-it looks like it is missing the front drive frange.

 

[82355]

You'll need another NP205 to swap on a fixed yoke.

Martin

 

[JDNobodi]

J B conversions sells a fix yoke conversion for $275. Which is about you could buy a whole transfer case for. http://www.jbconversions.com/index2.php?pc=3

 

[Mastiff]

Yeah, I saw the missing yoke, plus slip yoke needs to go. Didn't realize my TH400 wouldn't bolt up either. How are you guys sure my TH400 requires long input 205?