bent axle flange? pull the axle out and see if it's tweaked. Easy...pull off wheel, pull off brake drum, pull diff cover(let fluid drain), push the axle in toward the differential, pull the c clip, pull the axle out. If open diff, pull the pin, pull the spinders, then push the shaft in, and pull the c clip, then pull axle. There's different ways if you have an open rear vs. limited slip. You can replace just 1 axle. But I have no clue which axle you have(no sig). But I know 8.8" Ford's have different length shafts(DS vs. PS).
'01 XLT disguised as a '03 Fx4 Level II
Big. Loud. Slow. Bright.