Don't Do It!!!!
if there is any indication of where the fluid is coming from, you can figure out pretty closely what is wrong. If it is coming from the inside of the drum, I'd say it's a wheel cyl. cheap and easy fix. If it is coming from the outside of the backing plate, I would say possibly a cracked, or broken brake line or a loose connection/bleeder. If you find that the wheel cyl. has blown out, I would change them both (both rears). As for the MC, clean all of the fluid off of the outside, and fill it with fluid, then let it sit overnight. this should show any EXTERNAL leaks. if the problem is internal, the fluid will be coming to the interior of the cab. Also it could be a connection at the MC of one of the brake lines, or between the reservoir and the MC.
and be sure to clean the old brake fluid off of the drums.
I did the front brakes on my truck using a c-clamp to compress the pistons. one side got REAL tight, then POOF! brake fluid went everywhere. After cleaning up the mess and inpecting what happened, my fuel line had been rubbing against it for a while, and made a weak spot in the brake line. Glad that happened at home and not on the road. I blocked off that line (the line to the rear brakes) and it stopped fine. Finally, later, I swapped the line out.
stick with it. you'll get it dialed in.
