4l80 - t400 np205

[iroc12valve]

I have a 1991 gmc v3500 OBS right now its got a 4l80 up to a 205,
the 4l80 isn't right and needs a rebuild. (1300 using stock converter)
what i want to do is just put in a TH400 but i still want to have the 205, I have heard that 2wd 400 has a 32 spline output, and my 205 is 32 spline input . Is there something i'm missing (e.g. male/female shafts etc.)

Thanks

[65ChevyUtah]

Yes you are correct the 2wd Th400 has 32 splines. I used a 2wd th400 last year and hooked it up to my 205 transfer case and worked out great. I had a two wheel drive truck and I switched to a 4x4 frame using the same transmission. You need to make sure you have the th400 to 205 adapter. I am not a transmission expert but why not just rebuild the 4l80 ?

[iroc12valve]

Thanks for the info,
I'm not doing the 4l80 right now because 1300 is a little outta the budget and thats for a stock rebuild with the stock converter. it would be about 2500 to build a bullet proof one with a good converter, plus they're known for solenoid problems.

[iroc12valve]

does anybody know if the adapter from my 4l80 would fit with a 2wd 400 ? to keep the 205

[64swb]

to bolt up to a th400 with your transfer case/adapter you would need a 4x4 th400 that had either a np208 or later model 205 (like yours) behind it. the 2wd th400 will only bolt up to a 205 with the older figure 8 short style adapter. yours should be the later model long round pattern adapter. the output shaft on the later th400s for 4x4 are longer than the old style. iirc it was somewhere around the early 80s when they changed the styles of the adapters.

[raycow]

Maybe you need to research this first and find out what the all-up cost will be. If you have to buy a TH400 core and get it rebuilt, and then add the cost of the adaptor parts, I can see it easily reaching $1300. And after all that, you would still be giving up the overdrive and lockup converter.

Ray

[iroc12valve]

I can have a good 400 for $ 200 and i figured that if i can re-use my current 205 adapter then i would just need to lengthen my rear shaft( its a 2pc carrier bearing) i have other front shaft's so that wouldn't be a problem.