Tranny replacement

I'm about to replace my th-125 tranny with a used one from the salvage yard (less than 50k on it).
Car-parts.com lists many replacements out of models with 2.2 Liter engines. Does anyone know if all th-125's are interchangeable or do I have to find one out of another vehicle with the 3.1 Liter?

thanks

im doing my wifes 97 lumina tranny replace ment has 3.1 eng was told that there is difference from 97 to 98 ,if iwere you id look both over close an inch and a half difference is hard to see by eye ,been there most any salvage or parts yard could tell ya