I just starting having this problem a couple of weeks ago. When you accelerate it is smooth till 35mph and then the gear shifter starts to shake pretty bad, and the truck will put you in the right hand ditch very fast if you let go of the the steering wheel for any period of time. I just had new tires and rims installed, so i thought that was the problem, so i put my stock wheel and rims back on, and have the same problem. I had my truck up on the hoist in our shop, and everything is tight. I installed a new track bar 10,000 miles ago. I just also recently installed new Monroe Reflex shocks all the way around, could it be possible that one of them might be bad already? The truck has 124,000 miles on it. Any ideas? 
