I believe i pulled off a first, I broke an RC-Monster diff pinion

I KNOW I NEED DRIVE CUP, BUT WICH ONE??? For the diff pinion, it's easy, any 8mm drive cup will fit, but on the stock trany output shaft, you need a 6mm hole in the drive cup.
Could you find me a drive cup who'll accept a standard 8mm dogbone and having a 6mm hole on it???????

This is the main problem.

The guys who have a 1/8 style center diff or the "sliperential" don't have any problem, but the guys like me who have the stock trany have a serious problem to find a proper drive cup to fit the output trany shaft.