Chevy & GMC Vans

Ive got 2000 AWD and it has now just a slight vibration around 67 mph. I've had the tires rotated and balanced and also have had the front end aligned all at the same time. Its not as bad as before the service. The tires are not cupped or out of round and the rims are not bent. I have to also have my rear drums cut since they are warped. Could the vibration be coming from out of round drums or rotors? Thanks guys.............

Was the drive-shaft removed as part of the service you did/had done?

The drums are balanced in the manufacturing process. often you will see a weight tack welded to them.
If they are out of round, they very well could be the source of the vibration. could be a balancing weight fell off one of them as well. Also take a look at your drive shaft. You should find a balancing weight on it as well. If you don't find one, your drive shaft is likely out of balance and will vibrate, more so at certain RPMs than others.

Thanks guys

My thought was maybe the drive shaft had been re-installed out of phase. It it was put back in 180* off from where it had been, you could get this kind of vibration.