You might want to check out the rear axle on the Kawada 300m series of 1/12th cars,i think they use something similiar but i not sure.Go to www.kawadaracing.com
or go to www.kawadamodel.co.jp
kawada's home site in Japan(you may want to download a lang. translater like bablefish) and e-mail them.If you go to the kawadaracing site go to the 300m page and there is a picture of the rear axle and you might be able to tell if it is the same or close to it!! I am waiting for the Kawada 300m limited 2 come in now,it just got released in Japan and should hit U.S distributor soon.
hope that might help