While playing with my ..new to me.. B7500 HST I noticed a noise that appeared to be from the rear axle. Was moving some dirt and back dragging with the FEL, also in low range, and mostly in reverse. While moving under light to moderate load, the noise is a kind of "bang". Sounds like you smaked the center of the wheel (axle) with a hammer. Never noticed it till I put my home made ballast box on. ( only about 250lbs right now). I initially thought maybe the box was swinging on the 3pt and catching the tires, but ruled that out. Any thoughts appreciated.