Big or Small Block Chrysler - Internal Balance to GM transmission 130 Tooth - 8 Bolt Crankshaft 2.488 in. Center hole, for use with 80013 crank adapter Highly recommended for use with Ultra-Bell bellhousing SFI 29.2 Certified Superior in Strength 0.1875 in. Thick Chromoly Center Blank Hand Fitted and Welded Ring Gear 6 x 10.750 in. GM Converter Bolt Pattern Only, will not fit converters with large 11.500 in. GM Converter Bolt Pattern Precision Machined, Welded, and Balanced In House