Gary Schroeder made those. A standard would be 10 spline on the rear, but Steve Stapp had some made with the 6 spline. Danny Purcell might have one, he changed his out, or try to get hold of Steve, he might have one left, or call Schroeder Monday, if he has one he could overnight it to you, I know money is no object. Lots a luck, and no, it isn't an Acro! Bob