On the front, you'll need to remove the cap, might need to remove the dually adapter to get to it, then there will be a large nut on the spindle. Take out the cotter pin, you should be able to remove the nut. The drum/hub will come off. It may require some persuasion to come off, some light smacks with a hammer or work with a small prybar may help.
The rear will depend on what hub it has. Earlier models have 4 (I think) recessed slotted screws that retain the drum to the hub. Later models use the wheel studs to hold it on, and the drum is actually behind the wheel mounting surface of the hub. This type requires that the bearings be disassembled. For this, you'll need to remove the 8 bolts on the hub, then remove the axle. You can then access the wheel bearing nut, which requires a special socket (available from the flaps). After taking out the lock nut, locking ring, ang adjusting nut, the drum will come off just like the front.
I will suggest that you get a shop manual before you go too far into repairs, if you don't have one already. Your'e going to need correct tightening specs for the bearings, especially the rear.
