Stu is correct. There are lots of posts on this issue. What is unusual in your case is that your goal is the seals inside the brakes next to the differential and the goal isn't to simply change brakes.
The pins go all the way through the brake shoes and go into the casting for the rear end.
I've struggled with these several times and what has worked best for me is as follows. I removed the rear wheel and fender. I supported the main weight of the rear end with a bottle jack placed under the differential housing closest to the wheel removed. I then used a cherry picker (or engine hoist) to support the weight of the final drive and rear axle. I then loosened the large nuts that hold the final drive to the differential housing - don't remove them but have at least 1/8" space between the nut and the casting. Once these nuts are loose, try to break loose the axle from the differential. As soon as the axle is loose, work the axle around until the brake pin comes free. You may need to re-tighten the nuts a couple of times and then re-loosen to get the pin free. Mine came free almost immediately as soon as the axle moved from the differential housing.
I can't recall if the entire axle can be pulled without removing the brake shoes. I believe there is a problem with the linkage but am just not sure.