I need some help....I took my car on a road trip and ran a consistent 80to85mph for 5 hours and on the way home my gearshift starting vibrating and making noises. 3.73 gears are new within 2 years so I went in and had my drive shaft balanced (it wasn't off balance enough to warrant such vibration) so I took a transmission guy for a ride and he said it was definately a tranny issue. So knowing I had a blown head gasket also I decided to jump in with both feet and get it all done. Pulled tranny and the mechanic found input shaft and bearing needing to be replaced and all gears look great. Did a a motor rebuild and got my car back and it still vibrates at high RPM's. Can anyone add any input? Thinking flywheel needs balanced or harmonic balancer?