The #205x50 damper is designed for use in SBF engines using 50oz. externally balanced crankshaft. The damper utilizes the stock late model 4 bolt pulley pattern and the spacing matches the 94-95 Mustang accessory system. This damper is best matched for stock or modified engines producing up to approximately 1000 hp. For applications over 1000 hp please look at the #207 race damper.