At 50 MPH i get vibrations on my 97 4runner ltd. I took it to toyota dealer, they recommended that i changed all 4 tires. Bought 4 new tires, balance and align, still vibrations. Toyota said it could be the front end, the Diff, the drive shaft, or the tranny. They check all above, still could not find the problem. Does anyone have any idea as to why this truck is vibrating. Thanks