Jim G -
My sources tell me that what you want is a "Chevrolet spline". I'm told that Ford and Chrysler are different than a Chevrolet and that in 55, or earlier, and later into the 60's, steering box rebuilders builders and mechanics recognize the different splines by brand name. So, it seems that all you would need to tell them is that the spline you need is the "Chevrolet pitman arm spline". It sounds simple, but that's what I'm told.
Joe
