hi, I'm getting a vibration from the rear on the highway at about 60- 70 mph, usaually more noticable when I let off the gas and/or when I just start to give it gas. this started to happen after gear change. any help appreciated.

 

take the driveshaft loose and flip it 180

 

I already tried that and unfortunatly its stiil the same. only deoes it while i lay off gas slowly and just when i start to give it gas again. also when cruizing on hwy with low load (low rpm 5th or 6th gear) hear a kinda grinding ,light rattling sound. dont know if its driveshaft, u-joint seems fine or rear.

 

my buddy has the same problem in his 94 Z28 after we fixed his blow headgasket. Were Still trying to figure it out.

 

bent axle? tire out of balance? maybe when you removed if and dtopped it the weight fell off?