Help! Brakes for a 71 3/4 ton 4x4 w/leafs

[Scott McLean]

Please help me out it is killing me not to be able to drive my truck.
Here is what I have. A 1971 Chevy Custom 20 deluxe 3/4 ton 4x4 with leaf springs. I already went through and rebuilt the front brakes. Moved on to the rear brakes and to my suprise the previous owner purchased the wrong drums and placed them on the truck. These drums do not even cover up the entire brake shoe.Also the cylinders are seized no doubt from all of the debris coming into them from the gap between the drum and the backing plate. The axle is definately and Eaton with the round cover. Although I have no idea what size brake drums or shoes came originally on this rear end as the ones that are on it are obviously wrong, I do know that the depth of the drum needs to be somewhere around 6 inches. I heard that some of the ho72 came with no spins/Detroit lockers in them so I went for the test on a gravel road and both rear wheels dug wholes in the gravel which leads me to belive it is locked. I want to exhaust all possiblilities of keeping the rear end stock as I use this truck for its pulling/trailer towing capabilities. Any help?