They are a real b-yatch to get off. I ended up using a pair of hand pruning shears...you can wiggle the blade behind the edge of the washer and apply pressure, keep rotating until you have enought space made for a screwdriver. The heat treated blade worked well for me, after you do one they become a piece of cake...good luck!
Take a small thin screwdriver, or use your pocket knife, and pry the washer up a little. It's aluminum so they can be bent up easily. Then take a pair of wire cutters and clip it. Usually it just breaks where you cut it, then you can pry it off.
I replace mine on the diff and oil pan at every other change.