If your referring to the spline count on the pinion, because they did have 2 different counts, you can identify them by the pinion nut size. If it takes a 1-1/8" socket it's a 10 spline pinion. If it takes a larger socket (1-5/16" or 1-3/8") it's a 29 spline pinion. As others mentioned the axle splines are all 30 spline.