The Big block lumps have a seperate woodruff key. The small block camshafts have a dowel or tapered key cast into the pulley. I'll have a butchers at my mates big block pulley next to a small block one if i remember when im up my workshop.
Catcams do a billet alloy one with a dowel keyway. Or ppp and Dbilas do the modified OE fit pulleys (guaranteed good fit on the camshaft).
