I have a 2001 chevy blazer 4 door 4x4 and I have a violent vibration that starts at 60 mph and shakes bad until about 70....its not right off though, u gotta drive it 4 or 5 miles than it starts....any ideas?

And when it vibrated u can loom in the drivers side mirror and see the tire wobble

 

Slightly out of balance tire and/or a tire with non-uniform wear coupled with a worn shock perhaps? Here's a scenario to explain the delay; cold shock fluid will resist foaming & will dampen the vibration from the out-of-balance and/or badly worn tire. Once the shock fluid warms up through repeated high frequency, low amplitude oscillation, the fluid inside can foam, making for complete loss of axle damping.

 

So start by putting new shocks on it?

 

A good inspection of the tires wouldn't hurt as well.

 

Do u think it could be anyone.g possible i.side the rear end or no?

Stupid phones... Possibly inside the rear end?

 

Could be a slightly bent axle shaft if it is not the tires.