I've got a 2015 Taco with 93K on it. Automatic transmission. It's got a 2in lift and a Four Wheel Camper on the stock 5.5ft bed. About a year ago I started to feel a vibration that comes and goes rhythmically and very steadily around 65 MPH. Now it is worse and also is strong at 40 MPH. It happens when accelerating and decelerating. I had the carrier bearing replaced (it was loose) and the u joints and the the whole drive shaft balanced. I have new tires on the rig and it still happens. Seems fine in 4 wheel drive (I dont go 65MPH in 4WD tho) Any ideas? Transmission? Diff? Thx!