All six U-joint replaced. All spicer. I finished that project last night. There is no more low humming at 120mph do to two of the ujoints freezing up. Also no more stick shift moving around anymore. But upon taking it out for a short high speed run, while accelerating my rear end wanted to go to the right and I practically had to counter steer just to keep going sraight. My right rear tire was low on air 10 psi while the left rear tire was 35psi. That could have something to do with it. But the rear end still feels unstable. I also noticed my right rear tire has rubbed against the wheel well. My rear end looks like it has always sat lower than all you other guys ZR-1's do. It could be time for new shocks to. Anyway chew on that and see what you think.