I sent the one from Advance Auto Parts back and they refunded my money. I called AGR and they weren't much help, but I did find out that after reading the product description on Summit it requires a 36 spline so I'm going to give this one a shot since the description matches the specs for my application. Ecklers says 13/16 but no list of spline count so I'm gonna assume it's for an original with 31 splines.
http://www.classicparts.com/1967-76-...info/SS-5152/#
Jeff - the link didn't work. Website says it temp out of service