2wd TH400 to NP205 Adaptor

[Mattman2010]

I have a 85 gmc crew cab that I am converting to 4x4. It has a 2wd TH400 transmission and I have a NP205 transfer case that was behind a SM465 4 speed manual. I have read with the correct adapter you can hook up a NP205 to the th400.

So with an adapter like this work?
http://polyperformance.com/shop/71-8...g-p-20923.html

Now for the coupler I am not sure what you would do, I think I read that the TH400 has 24 splines, and I am not sure how many splines my NP205 has, Do all NP205's have the same input shaft, and the couplers are just made to adapt the output shaft from the transmission to the input of the transfer case? or would I have to find a NP205 that has 32 splines? Or is there a coupler made that goes from the 32 splines from the TH400 to the 10 or however many splines the NP205 has?

This is probably best in the 4x4 forum, but I figured more people visit this forum than the 4x4 forum.

Thanks, Matt

[mongoose]

2wd and 4wd trans' have different tailshafts/housings.. so unless you swap them out i don't think this part will be working?

[thepenguin99]

What is said above is correct. 2wd and 4wd trans have different length tailshafts. That adapter is a replica of the original GM part so it won't took up your 2wd trans to the NP205. Wish you were closer. I am pretty sure I have a 4wd th400 that I would trade for a 2wd version.

[csb#356]

If I remember right the 205s that hook to the turbo 400s Have a 32 spline female input shaft so there is no coupler shaft used. You can convert that 205 so that you can use it but you have to get the 32 spline input shaft and it has a larger diameter so you will also have to bore out the input bearing hole to fit the larger bearing and input shaft.

[Mattman2010]

I also have a TH350 with a NP205 behind it, I guess that NP205 has 27 splines on it. Would I have to get it bore out to fit in the bigger input shaft?

It sounds like on this link that only the SM465 NP205 needs boring, and the 27 splined TH350 NP205 does not.

http://www.polyperformance.com/shop/...t-p-20681.html

[csb#356]

both the th350 and sm465 transfer cases would need to be bored out. both input shafts are the same size just different number of splines.

[Mattman2010]

Well, I guess I will be sticking to swapping in the SM465 with the NP205 instead of trying to get the NP205 to mount up to the TH400, unless I could find a NP205 for a Th400 which I think is kind of hard to find. I was hoping it would be somewhat cheap, instead of cost half of what I paid for the truck. I was just wanting to use what I had, and would prefer an automatic over a manual, but the manual will be fine, and probably get better gas mileage than a auto.

Thanks for clearifying,
Matt

[Mattman2010]

From what I have read so far is you pull the tail housing off of the 2wd th400, and if it is a short tail (4.5 - 5 inches, somewhere around that) the adapter will fit onto the th400 and you can install the np205 to it.