autowagon

can anyone give me a driveshaft length for a 85 gsl automatic? my car was makin noise and the u joints seem fine to me but the yoke doesnt go in very far.when i push it in there is an inch or inch and a half from the rear of the driveshaft bracket to the rear end. it doesnt make noise with the heat shield off ,but i can still feel vibratin'. the driveline has a sticker from a local shop on it so my gues is its the wrong length or something. (casper,wyoming...tunershop heaven)