1990 G20 van transmission compatibility question

This van has a 350 engine. I was wondering what vehicles would have the same transmission. Its a Th700. First: is there a difference between the TH700 and The 700R4? or are they the same making it a TH700R4? The transmission was rebuilt 30,000 miles ago but its gone again. It was traveling on the highway after hours of driving and it just lost everything all at once. The fluid is full but very burnt. The same shop wanted 1800 to rebuild it again. They said it was something to do with the torque converter. Does this sound right?
Most of all I am trying to find a used cheap tranny so can someone tell me what will fit from what vehicles?

700-700R4 are the same.
They are overdrive transmissions.
91-92 should be close but.
Check with the salvage yard for what years interchange.

If it quit everything and fluid is burnt it is more than converter.
Walk away from that shop a good 1800 $ rebuilt should have lasted well over 30K.


If you want used check a known good local salvage yard that checks stuff out and give you a good warranty on it.
Some good ones also install them for you and put a good labor and parts warranty on them.
Good Luck
MT

Im thinking that the 700 r4 is the sam from the late 70s to the early 90s. I know the length id different in some cars but I think that the trucks had the same tranny as the vans.
Does anyone know what will fit a 1990 van?

Outside yes but a lot of changes inside.

Check your salvage yard interchange for what will work right not just a fit in.
MT

If its a 4 speed, cheap, and it fits that good enough. I had an old 1978 350 van and that tranny was still good when I sold it with 208,000 miles on it. Then the tranny lasted through the abuse of a teenager who toasted two motors and the tranny lived.
Otherwise the van I want to fix is headed to the scrap yard.
The salvage yards are not very cooperative when it comes to giving out the interchange information which is why I was trying to figure that out on here.

If its a 4 speed, cheap, and it fits that good enough. I had an old 1978 350 van and that tranny was still good when I sold it with 208,000 miles on it. Then the tranny lasted through the abuse of a teenager who toasted two motors and the tranny lived.
Otherwise the van I want to fix is headed to the scrap yard.
The salvage yards are not very cooperative when it comes to giving out the interchange information which is why I was trying to figure that out on here.

Check around for one that will help.
Some salvage yards are online and let you check inventory online,
MT

I found a 1991 gmc van with a 350. I took the transmission out and everything was the same except for the kick down cable and the speedometer connection. The new tranny was electronic. I took the tailshafts off and it appears it can be switched over. There is a plastic gear on one and a metal toothed ring on the other that is read by a sensor or magnet type thing. I want to switch them but I think they are pressed on.
Does anyone know if this is possible or do I have to go without a speedometer?

f you old one you tok out has the plastic gear and speedo cabel you need to stay with it.

The steel gear on the 91 transmission will have to get pulled off and use you old plastic gear.
They are pressed tight on tail shaft.
You may need a special puller to get it off.
Will you old TV cable fit on new transmission?

Yes the kick down cable was easy to change. I just need to find a puller. The one I have doesnt reach enough.

Yes a good puller or you may be able to crack it with a chiesel and hammer.
But wear eye protection and be careful.
Good Luck
MT

The metal toothed gear will crack?
I cant seem to locate a puller long enough to reach. The local store that rents pullers doesnt have it. They only reach 6 inches. I found them online, but I really dont want to buy it for a one time use.
Are there any other tricks to removing the gear?

Grind a couple of notches with a hand held grinder down close to the transmission shaft or cut a couple of notches in it with a hack saw.
MT

I found and article that told me how to get the gear off. I used a 1 1/4 open end wrench and tapped it off from behind. The plastic gear was easy except for holding the clip at the same time. The metal gear I had to actually hit the wrench with a hammer. I used the boxed end of the wrench to tap the gear into place and onto the clip. It was actually quite easy. I guess if you have too you can heat up the gear to expand it some but I didnt have to go that far. I did have a small propane torch ready just in case.