I may be able to use the gears, modded a bit. If I can get a set, I may try to use them with the next proto shaft. I will probably do this, as I can run one style setup in each of my trucks and see which one breaks first!
http://www3.towerhobbies.com/cgi-bin...?&I=LXTKP2&P=7
One side of the gear is recessed a bit, and only has those 2 ribs where the dog clutch engages. If I mill them out, I can reduce the diameter of most of the al adapter to fit inside of the gear, bringing the gear closer to the diff cup. I would only need a small amount of the adapter to be the full diameter, maybe .050" thick, it is currently .200" thick. I have a truck with a 2 speed setup in it, so I may have to rob the tranny out of it for testing purposes!