mikechef13

i have a 87 ttop gt. just got it 2 weeks ago. when i get up to maybe 50 or so in 4th and 5th gears, there is a vibration coming from either the back of the trans or the rear. i thought it was u joints, so i replaced them and it is still doing it. if my foot is in the throttle, it isnt there... but when i let off, it seems to not be there too. it seems to happen when my foot is on the gas just a little bit. the guy i got the car from said the guy before him put 3.55 or 3.73 in the back. the car is lowered, maybe a suspension problem??? no vibration in the steering wheel either. really frusterating...please help.