A friend has an old garden tractor that appears to have a '38 or so 3 speed tranny that's been adapted to fit. The nut that holds the input bearing to the shaft is shot and I'm trying to find a new one. There are many out there for the SM420 4 speeds, but I don't know if this is the same size. Any hint as to where I might find a replacement or if the SM420 nut will fit the old 3 speed top loader.

Thanks,

Stuart (atomarc)