Timmer,
If you don't have a "Shop Manual" (1948-51), ya gotta get one soon my friend.
All the info for removing the axle after removing the "hub cap" and so much more begins on page 4-20 of the manual.
Check out this free to use online copy of the
1948-51 Shop Manual and see/read up on your rear axle disassembly.
Everything you need, including the instructions to remove/replace the brake drum are right there at your finger tips.
NOTE: The online info is great, but sometimes hard to keep handy when out actually doing the work. A reproduction paper copy of the shop manual is readily available for a whole bunch of vendors from just a little money if you shop around and is great for having right "in hand" when actually turning wrenches.
Keep us posted on your progress.
Dan
