Rear Brakes?

[67ss&99ss]

Hello all. I am new to this forum. I have had my 69 CST/10 for years, but I have just started working on it. It is a short wheel base truck, 350, turbo 350, 12 bolt, with manual drum brakes. I redone the front brakes on the truck this past weekend and all went well. I replaced the shoes, hoses, wheel cylinders and all the hardware inside except for the adjusters. Now my question is, how do you get the drums off the bacK???? I couldn't get them off for anything. I sprayed pb blaster on the axle flange where it slips through the drum, let it sit, wire brushed the area to remove as much rust as possible, took a big socket and placed it over each stud and hit it with a 3 lb mallet, then tapped the outer edge of the drum repeatedly to no avail. The drum would not budge.(the brakes are not frozen to the drum. I can turn the rear wheels easily) This isn't a setup that you have to remove the c-clip in the axle and pull the entire assembly out just to get the drum off, is it? I've done brakes on my one ton dodge truck, but it has a dana 70, and all i had to do on it was unbolt the axle, slip it out, and the drum slid right off. The axle in this truck isn't made that way, so I don't know what to do. I'm scared to hit the drums too hard because I don't want to bust them. Advice?