TH 200 and TH350 share the same mount location, TH200 4R is the same length as the other two, but the mount is further back and requires a different mount and crossmember. Only 1985 and newer G bodies have the correct location on the frame for the TH200 4R crossmember, earlier cars will need to be modified. All 3 transmissions can use the same driveshaft. The TH 200 is not very good. I killed 3 of them with the 231 2 bbl V6. The TH200 4R can be good if modified right. As with most GM OD transmission designs, get the newest version you can find as there were improvements made over the years. Turbo cars had the best ones, but the MCSS and 442 models were also better than pedestrian models. Most will interchange to BOP and Chevy bolt patterns with the one notable exception being Cadillacs with the 4100 V8 engine. This was the first application of the TH200 4R and it is unique to that engine. That was around 1982 if memory serves. GM stopped using this trans in 1988 with the death of the G body ( IIRC) and went to the TH700 R4/ 4L60 (E) as it's exclusive RWD automatic in cars and light duty trucks. 3/4 ton trucks could get the TH400 based 4L80E in the 90's, but that's irrelevant here.
