94 Firebird Vibration at 45 mph

Hello when i reach about 45 mph im getting a very bad vibration it feels like its coming from the back of the car because I cant feel no steering wheel shake if I give it more throttle it stops or slow down it stops but every time I get up to speed it happens I replaced the right rear wheel bearing but I think I just wasted time and money.any one else had this problem with this vehicle and also have changed the tires around it didnt help.:screwy:

Did you have your tires and wheels balanced?

Moved to Problem Diagnosis...

also... :iamwithst

Check to make sure your wheel weights are still on the rims, and check to make sure your lug nuts are nice and tight.

probably the axle is bent

axle is probably bent