Brake drums for the 3/4 ton and 1 ton AD axles are pretty scarce and expensive when they can be found. I've seen some pretty nice conversions to disc brakes, front and rear, that allow you to upgrade the braking and use newer, less expensive replacement parts. If he's using the truck commercially, even with moderate loads, an upgrade would be a good idea, especially if the truck is ever involved in an accident.
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!