Q's on swapping TH-400 with 700R4

[VividVisions]

my current setup is '86 3/4 chevy 350 TH-400/208tcase

My trans is junk it doesn't move anymore, i want to go overdrive, the main use of the truck is to tow my sandrail to my cabin (200 miles) 90% of the way is highway. my question is do i have to get a different adapter?? what year transmission do i gotta get?? i heard there are diffrent spline output shafts?? do i have to do something to the t-case?? Nothern autoparts have a kit to make the lock up work for $130, is that a good deal?? any help would be appreciated, thanks

V.V.

[millerxc]

700s have a 28 spline output, 400s use 32, so you need different input gear for tcase and different adapter, length is real close so drivelines are probably gonna be Ok, good luck making a 700 last for towing, get a good warranty??

[Bo185]

Originally Posted by millerxc

700s have a 28 spline output, 400s use 32, so you need different input gear for tcase and different adapter, length is real close so drivelines are probably gonna be Ok, good luck making a 700 last for towing, get a good warranty??

Actually you mean 27 spline output shaft!



It will last for towing if you final drive gears are good and keep up with maint. and get a good cooler. And towing in OD is ok if it's pretty flat. I got 175,000 miles on mine with alot of towing and the guy I bought the truck from towed a hugh camper with it for 75,000 of those miles.

[VividVisions]

any idea where to find an input shaft??

[imiceman44]

Originally Posted by VividVisions

any idea where to find an input shaft??

I have a 27 spline input shaft if you need one.
You will also need a different adapter, the th400 adapter is 6 bolt round pattern, the 700R4 is a 4 bolt.
I might have that one as well.
Send me a Private message if you are interested in either of these parts.
IceMan