That may be real hard to impossible to remove, Miles.
By the very nature of a bush hog, the steel is exposed to the corrosive liquid from the plants then left out in the elements to compound that corrosion.
I had a batwing wheel assy that had to replace a couple years ago. I tried everything you mentioned, and after hours of heating with a torch, expanding the axle housing, and beating it with a 16lb sledge, I finally got it out.
Mentioned it to my service manager at the tractor/bushhog dealership, and he said they find those, and cut the axle housing, expand it with a cold chisel, remove the axle and then beat the housing back and weld it up...
Heaven forbid those manufacturers use some anti-seize.
