2000 Silverado 2wd vibration

I have a 00 silverado 2wd x-cab sb with a 7 inch fabtech lift, I recently developed a vibration in the driveline, being a 2wd it's only the rear. I've just had both front wheel bearings go bad, replaced both, drive shaft support bearing just replaced, tires rebalanced, still got a shake, and when you hit a bump in the road, you get a metal to metal sound, definately in the driveline, I haven't put in on the lift yet. Any suggestions? Forgot to mention that this truck has 115000 on the clock

i guess you could have a dent in the drive shaft i don't know how but sometimes you see the weirdest things. or maybe the universal joint is bad, check for play. im not sure if you have drums or rotor on the back i know they kind of went back and forth with that but your drum maybe bad. my girlfriend's dad and brother both have a truck like that and it took the dealership for ever to find out that there drums where bad and causing a vibration and it actually messed up the tires too.

Just a note, don't know how much it applies, but a lot of GM u-joints can't be "checked for play". I had a similar vibration in one of my trucks and I ckecked my u-joints, no play. A couple hundred miles later the front u-joint gave way. Replaced both u-joints and no more vibration. The trick here is that some GM u-joints have a plastic material inside that you have to melt out when you replaced them, just use a small propane torch. This plastic crud actually dampens most of the u-joint play that you could find by hand, however, on the road it still vibrates like crazy.

JMR