Porsche 28 splines don't fit aftermarket 930 size cv joints ! Fix is to use aftermarket,"inner race" from Empi, Lobro/etc., replacement in your Porsche specific, outer cv/stub axle assembly.This allows you to run virtually any length aftermarket axle, for your build, (easily shortened). If your NOT using a Porsche, Audi or VW t-axle,or an irs, that you want to upgrade, this is not pertinent. Cheers, roverman.