1999 C1500 Suburban, stock suspension. New front and rear brakes. New U-joints front and rear, new axle bearings and seals. Still have a vibration that you do not feel in the steering wheel, do not feel it if you accelerate quickly through those speeds, or slowing down through those speeds. Basically you only feel it when you accelerate slowly or hold those speeds constantly. Take your foot of the gas and you don't feel it. What could it be? It actually feels like going over rumble strips. Transmission problem? Rear Diff?
Please help!!
Please help!!