vibration

[D3ATH_F3YD]

I had the same problem, it was my rear diff dying on me. It blew out entirely on the highway and by stomping on the gas up a hill smoothed off the pinion gear entirely. I'd check the diff, just take out the bolts and have some RTV and gear lube ready to refill it after the inspection. Usually if it is the diff, you'll notice allot of burn marks on the gear faces (it'll look kinda melted or severly scratched) and metal slivers in the oil. If it's good, just put it back together, and check something else... like the engine mounts. I replaced mine just fine with allot of research, but swapping out a junkyard axel would have been just as expensive and taken less time.