Glad to help what little I did but sorry I have no idea of an original spec and it'd surprise me if you find someone who does know. The cone type sure grip was never designed to be a rebuildable unit and my guess is that's the reason there is no spec published. I have a 68 and a 70 factory service manual and neither give any specs. They just say it's a non servicable unit. I'd say we got lucky that someone figured out how to get some more miles out of one by shaving the ends down. If yours has .030" clearance I'd say it's in pretty good shape as all but one I've torn apart had the cones bottomed out.