Originally Posted by fomocofan
Just look at the outside between the studs...31 splines will be flat with two little holes, 28 spline will be hollowed-out.
Thats the way I used to ID the axels, like on my 64 post car, but I think you can't rely on that menthod on the 70s and later. I just purchased new side gears and spiders in 28 spline and am waiting for bearings. If the old marking system still holds true in 79 I'm screwed as mine has the dimples.