Bruce,
There could be 3 flat head screws in the face on the drum holding it to the hub.
On extreme cases I have used a 5' piece of 3" heavy wall pipe as a slide hammer. I get under the truck and rest the pipe on the leaf spring and hit the outer edge of the drum by sliding the pipe back and forth across the spring. With the heavy weight of the pipe and the spring holding it up I have good control and don't normally hit the backing plate.
Mike
