spurs and pinions

[oakey4]

our boyo has stripped a spur, the car is a mardave vrx ce it has a 73 tooth white delrin spur 48dp, why can i only find ones for sale upto 50 odd strange, if this is the case and i bought a say 52 tooth spur what size pinion should we buy he only has a 25 tooth pinion at the mo, cheers lads he is running 1s lipo, 12t ezerun combo if this helps...