Hi. I just picked up an 88 TBI350 with a TH400 attached. It is a 2WD version and is marked HD. I would like to know how I can convert it to 4wd so that I can attached a 1ton NP205. Anyone do this before and can you shed some light on the matter?

Thanks!
Chris

I am by far not a 400 god, but I am sure your gonna have to change the long output shaft to a short shaft. If I'm not mistaken there is a longer tailshaft housing thats gonna have to come off. Your also going to need the adapter that mounts a 400 to a 205.Don't forget driveshaft mods also......:skull:

Originally posted by tys
Hi. I just picked up an 88 TBI350 with a TH400 attached. It is a 2WD version and is marked HD. I would like to know how I can convert it to 4wd so that I can attached a 1ton NP205. Anyone do this before and can you shed some light on the matter?

Thanks!
Chris

It can be done. Which 205 case pattern do you have? figure 8 or circular? What is the spline count on the trans. tailshaft? Advanced Adapters in Cali. makes adapters to do this.:beer: :D

If you have the short tail shaft I have a NP205 and the adapter to fit it.

as long as it is a short shaft 2wd with bolt on yoke you can use the older 81 and older factory style (hour glass adapter opposed to the round) and it will bolt right up, if you want to use the round bolt pattern style you will have to change it for a shorter shaft

Well I went out and counted the splines on the shaft he gave me. He said it was a short shaft, but after placing it next to the trans, and lining up the speedo gear with the output, it is obviously longer than what is in the trans to begin with. The spline count was 27 on the one given to me as well......so I think he screwed up.

Anyways I'm intrigued by what BigBlock is saying. It appears to be a short tailshaft TH400, and the yoke is bolted to the end right now. I will take a picture tonight for you guys to check out.

Thanks,
Chris

27 splines? I didn't think a TH400 ever came with 27 spline outputs... I know that TH350's and TH700R4's did though....

I could be wrong!

Squash

You are correct, TH400s came with 32 splines. I was given an additional shaft and told it was a short shaft, but didn't count the splines until I got home (3hrs later). I believe I was given a TH350 long shaft as 350s and 700s are 27 spline.

Thanks,
Chris

I bought a 205 out of a bone yard that was behind a T400 and had 27 splines a long time ago. The truck was a 1980 half ton with a BB and the T400 in it. The BB and T400 where obiously swaped in and the 205 was orig. because it had the slip yoke rear. There was a 3/4" to 1" adapter on the back of the trans that went from the 5 (or 6) bolt 400 patern to the 4 bolt 350/700 pattern. I took the adapter for future reference. So (now my question), was that trans a 2wd short shaft that orig. had the yoke on the end? Do you have to cut the threads off the end of the shaft for this to work? See now I want to swap in a 400 and would like to utalize my existing T-case if possible.