My buddy has a '84 C10 with a 6.2/700R4 tranny. This is the second time in 4 years that he has had a 700R4 go bad. I have a 32,000 mile '85 CUCV wrecked parts truck with a TH-400 that works great. Can we swap out the TH400 for the 700R4 directly. If not, what's involved? His truck has factory 3.08's and he never uses the OD anyway, so that is not an issue. Thanks!

Simplist thing I know of is differnt driveshaft length. also your CUCV is 4x4 and his is 2wd, so the tail end might have to be changed as well? differnt axles mightve used different U/V joints?

TH700R4 = 23.4" length
TH400= 24.37" length

the selector on his sterring column might be an issue. I heard of hard or improper shifting from such swaps just because there is either a added gear, or one missing on the selector. not sure whats true about it, just keep in mind.

No, they are both 4X4.

You will need vacum regulator assembly along with the other stuff mentioned.

The donor truck had most of these these parts you'll need. Flex plate,dipstick & tube. Obtain correct output shaft gear & matching gear on the speedo cable for the 3.08 ratio. Find a 12 Volt key on source for powering the detent switch in the 400 trans.You will need to wire & install downshift switch above the throttle pedal,wire on down to L.H side of trans terminal. Install metal line from trans modulator up to the vacuum regulator valve on the FI pump & on to the vacuum pump.Set the vacuum by the book at the valve on the pump!!! The steering column parts needed for the 400 detents should be from the donor also. Also the rod from sc to trans lever.The truck will crawl from a stop compared to the 700s low gear ratio & less rotating mass. The 400 trans sucks up a lot of torque & horse power !!

No, they are both 4X4.

Sorry about that then. you said C-10 so I figured was 2wd. Sounds like you have mostly everything you need.

I dont see why hes blowing through so many 700R4s so quickly. they arent that bad of a tranny. unless hes abusing it or towing heavy and hard with it.

Sorry about that then. you said C-10 so I figured was 2wd. Sounds like you have mostly everything you need.

I dont see why hes blowing through so many 700R4s so quickly. they arent that bad of a tranny. unless hes abusing it or towing heavy and hard with it.

I think that's pretty much the case. He does a lot of heavy towing, the 3.08/700R4 aren't really the optimum gears for that. I should have said K-30. It has 33X12.5/15's to go along with those high gears. He killed the last one trying to back a trailor up a hill, and burned up reverse. He needs a bigger truck, but he wants to see if the TH400 will hold up better, so I sold it to him:confused:

TH 400 will have to have a special pump mod or it will lose reverse as well with a heavy load up a hill.

You'll have to swap the transfer case also. The 700 has a smaller diameter output shaft than the 400. There is an adapter set for this swap but the trans has to be disassembled to change the shaft.

Or use the larger input gear for the transfer case, to match the splines on the output shaft of the trans. Either way, you've some disassembly/assembly work to do. Assuming it's a 208, both input gear sizes should be readily available. The shift forks in the t-case should be check while it's apart. They wear the plastic inserts off rather quickly when loaded heavily. Can lead to "jumping into neutral" under load. Bad deal!