I have a 1995 Z-28 with the t-56 speed with 30k original miles. Around 80mph i can feel a vibration through the shifter and if you go faster, it can be felt throughout the whole car. ive already had the driveshaft rebalanced, and it did nothing. new tires and nothing. ive heard that there was a recall on something in the driveline butdont rememberwhat it was on. I think it could be the yolk. PLEASE HELP ME OUT!!!

 

Drop out of gear at that speed and let the engine drop to idle. If the vibration is still there while coasting, then it is coming from the running gear. If the vibration goes away, then the engine is probably misfiring under heavy load. Also make sure the motor mounts, transmission and torque arm mounts are good.

 

It could be a burnt valve. that happened to me once

 

could be any of those things! Hope its not the tranny! You could just put an aluminum drive shaft. Since the LT's have a steel one you can sometimes feel the slightest imperfections a bit more. I had that problem on my old 94z and when I didtheswitchit went away.