Hi Mark,
The Inner Demon 32 -TEF, is the part I am using it is very new and available from Inner demon direct. This geardive has been developed using the C-50 motors and should work well.
Hi Darrell,
Stick with a single Hacker C50-14XL+6.7 Acro motor. Use 10S4P Thundr Power and the master 90-O-Acro controller with an 21x14 APC-E Prop this will fly your P-51 with authority( Better than Saito 180), only limit is you must fly with mixed part and full throttle, as the system will pull 65 amps WOT.
Best Regards,
Sean Plummer
http://www.hackerbrushless.com/