The stock tranny is belt drive, not very efficient. The belt slips and rips very easily. The pede tranny is a geared tranny and also accepts traxxas slider driveshafts, so it is the best tranny for modding.
I have the pede tranny in my tube frame TLT...also have another one sitting around with my spare TLT axles. Maybe if I have time tonight, I will whip something up.