I put a 200R4 in to replace my 3spd. Had been having problems with center bearing (because I had put in mewer bell housing with rear tranny mount, and the mount was bad). Here in WA any tranny is $50 from a pick and pull next door, pulled pan on 1st 200r4 clean, would not shift to OD, returned it for another, had a vibation I did not like, got a 3rd one, teriffic. 200R4 is longer, did not want to pay driveline shop, splines were different. Pulled a couple of shafts, one I used was from a 4door chevy, mid 80's. if was about 3 1/2" too long, so shoved v8 up to front mounts plus a little, running electric fan from citation, no problem. newer rear u-joints are bigger, but napa sells u-joint with old and new diameters, pretty common. I have a panel, after being under about 100 gm cars, I'd say there are probably 30 different driveshaft lengths on 80's cars!
Here is a link that everyone should have that tells you everything you should want to know about GM automatics: http://my.en.com/~thall/olds/oftrn.htm
