just bought an 02 blazer 4wd from my dad who bought it from my brothers ex wrecked and he fixed it. It's got 60,000 miles on it. Original owner. There's a vibration when I'm accelerating right before it shifts any idea what it could be? There's also a kind of whirring sound on the high way that kinda goes in and out over and over. Any help guys? Thanks

 

Check the Fluid in your Rear Differential, I'm having the same issue, and it looks like i'm leaking from the pinion, which seems to be a common problem on the blazers.