Brakes working?
 

I just went out for a ride in my truck. When I got back I looked at the brake drums in the back. The rear brake drums closest to the sleeper were shinny and looked like they had been used but the furthest most set did not. Is that normal?

How far did you go and how many times did you use the brakes? How much "wear" did they get? Common sense would say that you should use a "brake stick" so that you can activate the brakes and walk around the truck to inspect what's going on. Measure the rods, then activate the brakes using air (and don't forget to chock the wheels), and measure them again. If they have the right amount of travel, they "should" be good.

One of the things my brother did before ABS was get the tractor moving on a gravel road fast enough that when he stood on the brakes, the truck would slide for about 2 feet. Then walk around and see which wheels slid and which ones didn't. Haven't tried that with ABS.