The only 3905 tranny cases in aluminum that I know of are the RD Logics ones that have already been posted. The only rear suspension arms that I can think of besides the RPM true track that does away with the rear turnbuckles are Racer-X ones.
The only rear suspension setup I know of that gets rid of the rear turnbuckle is the UE (Unlimited Engineering) RacerX setup. It eliminates the rear turnbuckle but adds one on the top arm for adjustability. Here ya go...