kocking from rear hubs

I got home that evening and he told me that after his days work the wheels were loose again. I took 2 of the grade 5 bolts out. He had used a 3/4 drive with a long handle and streched the 5/8 bolts to a point they were only about 3/8 in the middle. Now, those grade 5 bolt were old and pited with rust, I had used them one day in a hurry, always intended to exchange them for grade 8. Yes, grade 8 very important especially when you have a young lad with a big wrench. I have a 6' railroad crowbar, my grand father got it when he was a young man. Through 4 generations, the 4th generation was the first to bend it. He sheared Christmas trees every summer as a teenager, that job tends to put arms and shoulders on one, much like a body builder. After that I always had fun kidding him if we were doing wrenching. I'd tell him to use a 6" handle for tightening wheels.

Might be loose axle. Jack the tractor under final drive, pay special attention as the weight comes off the wheel. When wheel is clear of ground then try end movement on the axle. If the axle is loose, you best not run it until fixed.

Let us know what you find, I'd check for loose wheels first.