Can't help you with the numbers, but back when racing mowers was a thing around here, nearly all the guys swapped in the same transmission and rear axle assembly. Mowers are pretty easy to swap stuff around in, from what I've heard. I'd be willing to bet a search of racing mowers would provide a lot of useful information, those were the guy doing the grass roots swaps. I doubt your going to abuse your lawn mower as much as those guys that raced them did. They swapped in stuff that held up under racing for several seasons, should last forever mowing the grass. Gene