[quest]

Wow, it does not appear that you ever got an answer to your question on how to remove the rear drums.
I assume by now you have your manual and the drums are off? but if not.....

This is a full floating hub system, the hub and drum are separate from the axle. The center of the hub has bolts holding the axle in place. there may be tabs holding bolts from turning and you will have to bend these away from the bolts and remove them all. Have an oil drain bucket under the hub as gear oil should start to drain from the hub when you pull the axle out. The hub and drum will stay in place.

When you look inside the hub you will find a bearing retainer nut with a lock ring behind it. The lock ring will likely have at least two or more tabs bent down over the nut to hold it in place. use a screw driver and tap them back just enough to allow the bearing retainer nut to turn. don't bend the tabs all the way back they need to be able to be bent back down again.

After you have the assembly apart you can wiggle the hub enough to fish out the outer bearing and then just ease the whole hub and drum off of the axle housing. When re-assembling pay close attention the the instructions in the manual about bearing adjustment this is very important.

Also very important attach a note to your steering wheel to top up your differential gear oil before driving the truck. I made this mistake once and trust me you will only make it once!

(Also the front drums will have retainer screws holding them to the face of the hub.)