Don't know if you got any response on your question about the rear cylinders or not. I did mine a couple years back when I woke my truck from a 20+ year nap. Pretty straight forward actually. My truck is a 53 2 ton Cab Over. Probably not exactly the same as your 46 but brakes are brakes right? Got some kits at NAPA. Two cylinders on each wheel. I think they're 1 1/2" diameter. Hardest part sometimes is getting the wheels and/or drums off. Big hammer and a piece of firewood helps. Anyway, good luck with it.

Geo