Bent rear axle?

[imalumberjack]

So I'm just starting to drive new (to me) truck around ...... had a wobble .... when driving I could look out back window and see drivers side rear inside dual was moving side to side (difficult to see without crashing) sooo today I jacked up that corner started truck and put it in gear and went out to look .... definite wobble, both wheels .... I tried to hold something along inside hub where axle mounts but with tire shaking and stuff moving I got scairt. With truck turned off and brakes released I cannot move tires up and down as if there would be play in bearings. Next step is to pull wheels off and drum and take a peek ..... if I pull axle how would I know if its bent? Truck came from Ritchie Bro. and was not running and I have seen them when loading ...to get truck straight on transport trailer they push on a wheel with loader ..sometimes pretty hard so I'm thinking they might have bent an axle that way?
Any thoughts?