Mike, first of all, make sure there isn't a small screw holding the drum to
the axle. I recall on my 86 Trooper, there was one on each side... of
course, take it out if you find one. Next, where are you whacking the drum?
You should be hitting the drum right between the wheel studs, and in order
to do that w/o hitting a wheel stud, you'll need either a large, flat punch
or real good aim with your hammer - I'd recommend putting a couple of stud
nuts on the studs to protect them from a wayward whack. Finally, hit it flat
and hard - and don't hit the end of the axle, or you'll mushroom the axle
end, swelling it, and you'll never get the drum off. The goal is to hit the
DRUM in the area of the axle, between the studs and right around the axle
end where it sticks through.. as that's where it most often is stuck.

If all else fails, I've used a blue-tipped wrench (O/A torch) to gently heat
the drum around the axle and break it free... but only as a last resort.
Hope this helps.
R/
Steve