front, aren't they the same apart from the casing though? The kit came with the 36 tooth pulley, but you cant buy the gasget & screws without getting the pulley set (part 73481). Then you've got to get all the internals
72445 HPI Diff Shaft 6x25mm R40 (2)
86032 HPI Bevel Gear Set Gear Differential Savage 21
6811 HPI O-Ring 6x9.5x2mm Black Savage 21 (8)
Z260 HPI Pin 2.5x12mm Savage 21 (12)
+ diff fluid, etc
seems like a lot to outlay for 1 gear but on my track it'll make a big difference