almost as soon as i bought the truck i noticed and felt a thumping/bumping in the rear of truck under axle. i took it to local toyota dealer and was told there was nothing wrong. needless to say until i got recall after recall i never went to another toyota dealer. the people treated me as if i were stupid. like i was causing the problem. ive owned many trucks of almost every brand in my 57 years but never had on the when you accelerate the pinion angle changes dramatically when the axle warps under torque. i have since added helper spring kit from helwig and it has helped greatly.. but i know toyota knows about this. and as far as i know has never fixed it.. ive taken the truck in for all the recalls toyota has issued. i guess they needed to save a few bucks on springs. hope it was worth it to you toyota!