The first thing to do prior to tear down is to measure the ring gear to pinion backlash so you can set it back that way upon reassembly.
Axle tear downAxle rebuildYou can pick up a lot of spare parts via ebay for pretty reasonable. I did have to go through 3 rear ends from '41-53 to come up with a matching set of good sidegears. There are very slight differences between the years. Some gears have thrust washers behind them, others have a slightly thicker gear.
Most of these parts are either good or pretty obviously bad. A little pitting in the teeth won't hurt.
They are pretty easy to work on other than everything being so god damned heavy.
Jeff