I have been around sprint car racing a while but just getting into watching midgets. I see that there are 31 and 36 spline rear ends for midgets. Is there a reason to use one over another or are they used in different situations? Or is it just a change in technology; stronger, lighter, faster, ect?

Thanks!

36 spline came out as a stiffer option to eliminate some flex of the smaller dia 31 spline

Also some people had problems with the 31 breaking at the shoulder of the splines. Axle is substantially stronger and better tolerates the power levels of the newer motors.

Makes sense, Thank you