Welcome to the forum! I moved your post to this new thread so that your post gets more noticed. Unless there is something wrong with the engine you shouldn't have to touch the bottom end. The transmission is a weaker link than the engine.
The late model Riviera's are front wheel drive and you can find the Riv gallery's here. http://rivperformance.editboard.com/f3-showroom
1998 Supercharged Riviera - Custom CAI, Alpine spx-13ref, Infinity 6x9's, Alpine 4 Channel Amp, Kicker KX3, Silverstars, STB, Hawk Brake Pads, Monroe Air Shocks, KYB GR2