I need some info concerning a OD tranny swap and tranfercases.
 

I have a 86 Chevrolet 1/2 4wd truck. I believe it had originally an overdrive tranny in it. Reason being it has OD on the column shifter, and the rear driveshaft looks to be 2-2.5 inches to short. It has a T350 in it now, but its bad. So I heard that in order to hook a 700r4 to the transfer case I would need an adapter. See I am not for certain they didn't swap the case when they put the 350 in. are there numbers to look for to see what type and year it is, I am wanting to put back in the OD so I can get a little better MPG on the HWY. But don't want to spent a fortune doing so.
Hope you can make since of what I trying to explain.

Re: I need some info concerning a OD tranny swap and tranfercases.
 

700 r 4 will bolt in place of a th350, you can use the same t case. you will need the 700r4 TV cable. If you dont hook it up correctly you WILL burn up your tranny in a matter of a few miles.

Re: I need some info concerning a OD tranny swap and tranfercases.
 

So basically there all the same all the years?

Re: I need some info concerning a OD tranny swap and tranfercases.
 

No, they're not.

Outer dimensions are the same, but the earlier transmissions suffered many internal failures. If hunting for a 700R4 go for a 86 and later transmission. Up to 91, will all work. In 91 Gm changed the name to a 4L60, but it will work for you. Your truck should have had a 700R4. BTW, a 700R4 will NOT bolt into place where a TH350 was from the factory! The 700R4's tailshaft is longer and will bottom out on the t-case before you can bolt it together. The tailshaft housing that bolts to your T-case will fit a Th350 and should physically bolt up. Problem is, you wouldn't have enough spline engagement, as the Th350's tailshaft is shorter than the 700R4's. So in a nutshell, you can put a Th350 where a 700R4 was, but not reverse it without building a spacer, swapping out the tailshaft for a custom one or cutting the factory 700R4 tailshaft.

Re: I need some info concerning a OD tranny swap and tranfercases.
 

Thanks grendel, It had to had a 700 in it before because the driveshaft is too short. I can see atleast 3" of drive shaft yoke sticking out of the transfer case. So it makes since that it had originally a 700 in it. I had heard about the newer 700s so I will look for a 86 up. Thanks