[kbailey]

I'm looking at buying an '81 3/4 ton chevy 4x4 to drop my 3.9 in for daily driving. I believe the truck has a th400 trans and np205 t-case. I read through a lot of old threads and I couldn't find what I was looking for so here is my question(s).

1. Since this trans is behind a gas engine what all needs to be changed so it will work with the 3.9?

2. If I use a th400/th475 from the breadvan instead of the trans already in the truck, will it bolt up to the t-case?

3. Suggestions for a different auto transmission?

Thanks,
Kyle

 

[jessejonassen]

Using the turbo 400

All you have to do is take the governer out of the bread truck 400 and put it in the new one, and swap the modulater in the pick up for the adjustable manual modulater in the bread truck> They are both on the right side of the trans, The modulater will have a bolt going through a steel clip that clamps it in on the front right of the trans. On the back right is the governer cover with 4 bolts after you remove the cover the governer just slides out You just need to swap these to things and it will work, But it is much prefered to use the torque converter from the bread truck also. This is what I did in my truck. Sorry about my spelling.:rasta:

 

[rbarnett]

I'm looking at buying an '81 3/4 ton chevy 4x4 to drop my 3.9 in for daily driving. I believe the truck has a th400 trans and np205 t-case. I read through a lot of old threads and I couldn't find what I was looking for so here is my question(s).

1. Since this trans is behind a gas engine what all needs to be changed so it will work with the 3.9?

2. If I use a th400/th475 from the breadvan instead of the trans already in the truck, will it bolt up to the t-case?

3. Suggestions for a different auto transmission?

Thanks,
Kyle

You will have to use the output shaft from the 4wd Turbo 400 to mate with your transfer case.
You definitly need to use the torque converter out of the van also.
Bob B