03 Ram QC 4X4 shakes at over 60 MPH

My truck starts to shake at over 60 MPH. Up to 60 it's as smooth as glass. I have had the tires balanced 3 times, had an alignment done, changed the rear tires, swapped the spare tire with the front tires and there is no change in the shaking . Checked the driveshaft its fine, u joints are tight. Ball joints and tie rods are tight. The only thing that seems a little off are the inner half shaft joints seem loose and have a lot of movement. What is the tolerance in the inner joints? When I grab the half shaft and move it, it moves about an inch in each direction. I bought the truck used with 131,000 miles on it and I do not have any history on what has been done to it in the past.

Thanks for any other ideas about what to check.

If they are loose they are probably shot. Also you could have a bend drive shaft or a u-joint thats locked up. I would pull the shafts off and have a look. If not your going to bust up the transfer case case. If you do have a bad u-joint only get the none greasable style, they cost more but you won't regret the extra cost later.

had a mystery problem like that..turned out to be water in the tire

Thanks for the suggestions, I will check those items. I am pricing out half shafts now.

mine did the same for over a year before i figured out it was the axel shafts . i replaced front driveshaft and other things . does it smooth out when u put it in 4 wheel ?