Some drums are riveted to the hub. If that's the case, either grind the heads off the rivets or carefully center-drill them to release the drum. It's probably not necessary to reinstall the rivets if the center hole of the new drum is a snug fit on the hub.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!