I have had to pound mine on. Actually, usually have to.
and use a 3/4" breaker bar
with a 4ft pipe on it,
me laying down
with my feet firmly planted on the frame
and yanking for all I'm worth.
Wear a helmet.
Yes the socket should be shaped the same as the BJ.
Yes there are three sizes; one each for 72 and older Arms, 73 and newer Arms, and pick-up trucks. I can't see how anyone could mix them up.
I wouldn't use an air impact on it, in situ, on account of, if the socket blows up, it's coming for you.