Found out they are filled! Guy I bought it from had never mentioned it (and I guess never asked).
Got the tractor jacked up, got all the nuts off one side and popped the wheel off and
this thing felt a little heavy. Sure enough, wiggled it around a little and could feel the fluid sloshing around.
Needless to say I put it back on (not easy).
I think I will just keep these on for now. The rears where not in as bad of shape as the fronts. The weight may come in handy this winter pushing snow.