Replacement tranny

I have a "89" Reatta with 260,000 miles ,and a "91" with 118,000 miles . I read from a previous thread that the "91" is a electronic trans. ,and the "89" is not! What is the diff , and can I use the "91" in the "89" ? THANKS !

No you cannot. You answered your own question very well.

If you are looking for a replacement transmission, any automatic behind a 1988-1990 GM car with a 3800 engine should be "plug-n-play", this gives you thousands of choices. There is one consideration, the final drive ratio.

Your 1989 Reatta has a 2.97, other GM vehicles had similar ratios, Riv had 3.08,

I think if you use the sending unit that comes with the transmission, you speedometer stay correct..... but then I could be incorrect.

Thanks Barney !

I have a "89" Reatta with 260,000 miles ,and a "91" with 118,000 miles . I read from a previous thread that the "91" is a electronic trans. ,and the "89" is not! What is the diff , and can I use the "91" in the "89" ? THANKS !

Yes you can I have done it. It takes a bit of work but if you want to you can do it. You have to piggyback a 91, use the driver side axle, and passanger side transmission mount. from a 91. Also a little welding to the donor mount. Like I said it can be done.

My 89 Riviera has a 2:84 axle ratio