I’ve done what Jerry suggested before. It’s the best way to find out where the issue is.
Just make sure you have some safety issues covered. I would get a trusted friend or family member to be in the cab just in case. But not the wife!
Good cribbing under the axle and a back up on the frame. Give it a test run and then give the truck a good shaking side ways and front to back.
Don’t get too close to the tires or the spinning drive shaft, and you’ll be fine.
Better yet, find a mechanic with a lift and do it on that.

Rotational problem? Give me a break! Hope your mechanic didn’t charge you for that advice.
Don

1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!