Also what you really have to watch out for, is over the years the material on the inside of the brake drum has worn down. This leaves a lip around the outer edge of the inside of the drum. The shoes can't clear that lip unless you take all the tension off of the brake shoes. Often times, you have to disconnect the rear brake rod to get all the tension off the shoes so they will open up enought to be able to clear the rear drum. I've had it happen several times. Before you put your drum back on, make sure to machine or grind that lip off of the inside brake drum or you may have the same problem.