Oh, one last piece of valuable info:
I made a mistake and searched for weeks to find the best deals on rear wheel cylinders....only to find out they were for the base 15"x4" rear brakes. At the time I didn't actually know how to remove the drums, and they were too heavy for me to just "experiment" with. so I assumed their size.
After going through hell to get the parts, I come to find I have the optional 15"x5" brakes........all of those darn cylinders? WRONG PARTS
If you can, tear apart brakes first.