Well, I got a little time (and warm weather) to work on the car today. I attempted to pull the driveshaft out but it was stuck in the trans. After I pryed it out I looked at the splines in the yoke and they are twisted, the tailshaft is fine, no bad bearing like I thought at first. The yoke was wobbling on the tailshaft too, I guess that's where my vibration was coming from. I've had a vibration in the drivetrain ever since the car was brand new, just wondering if this yoke has been the problem the whole time. Time for a new yoke and then see what the next weakest link is. GM put the crappiest drivetrain in these cars.