Rear axle movment??

[64stpside]

So i just found out on my 64 c10, with the rear wheels off the ground , I can grab the right rear tire and move it in and out about a half an inch or better. The whole wheel , drum, and axle are moving. Went to the left side and there's no movement. What's going on? There's no whining in the rear end when driving at all , no fluid leaks. Could it be a bad axle shaft bearing? The reason I asked that is that I just redid all the brakes on the truck and put new shoes on, and on that right rear ,I put a new drum on. When spinning the wheel to set the adjuster it free wheels until it gets to a certain spot and then you can feel it drag on the shoes. I'm wondering if the bearing is bad and is letting the axle drop down to the point where it makes the drum touch the shoes when I'm rotating the wheel.