I have a 9" rear in my '56 wagon that was narrowed & really built for a high HP drag racer. I can't stand the detroit locker any more so I bought a 31 spline 3:70 posi. I didn't realize that the hi Hp race cars may use 33 or 35 spline. Is there any way to tell w/o pulling an axle ? The rear wheels & tires are WAY too big for me to handle so I want to be sure the one in there is 31 spline .