I'm not sure that the doubles are needed on the top (wonder where this transmission comes from: I've done an awful lot with douple orings on the bottom plungers only) If the thing's together right, it doesn't seem to me that it would ever be necessary to have the extra seal on the top.
I've had these Snap-on pliers for years- used to do truck transmission a long, long time ago. They work well for the eyeless snap rings retaining the drive spools. You can always save the next guy some work and replace the rings with standard eyed snap rings when you put it back together. I'm sure there's a reason that they used the type they did, but I've never had one of the others come apart and they make life lots easier.
Stuck in the seventies- not in the swamp.
(6) Attex, a Hustler, a Super Swamp Fox, (2) Tricarts, (3) Tri-sports, a Sno-co trike, 3 Dunecycles, and a Starcraft! ...so far