I had a poping noise on the driver side rear wheel on my 94 vette i had the wheel bearing and u joints replaced now i have a vibration at 55 to 58 mph did not do this before

Yea like he said or you can go to O'Reillys auto parts or AutoZone if you have one close were you live at.

it could be a bubble in your tire and you can't fix that you have to buy you a new tire.

when removing the driveshaft/s from the car/vette before attempting to work on the u-joints. Because the driveshaft is balanced as a unit, *mark* the pieces so you'll be able to position them the same way when reassembling. Before replacing the u-joints, be sure they are oriented correctly. Nothing is more irritating than going to all the trouble of replacing u-joints and then finding you have to do the job over.

I agree with Kelly. Have the rear half shafts checked. If you changed the bearings and u-joints, that will alter the balance. There are specialty shops that can do the checking, but it will be expensive, but vibration can cause major money damage if left alone. The yokes will stretch and the u-joints will go out again, among other things.