It is not very difficult:
Remove rear wheels and brake drums.
Remove differential cover (after draining oil).
Remove lock pin, pin, and spacer block from differential.
Push axle inward toward differential.
Remove C shaped axle retainers.
Pull axle out of axle tube.
Use a seal puller/pryer and remove seal.
Replace seal.
Repeat in reverse order for assembly.
I think I covered all the basic steps and remembered correctly.
