This is a FORD  3 GROOVE CRANK PULLEY FOR A  289 CUBIC INCH ENGINE FOR 1965 1966   THIS FITS FORD MUSTANG  and FALCON.

This pulley is unique to the Mustang and Falcon, with a smaller outer (Air conditioning AC A/C ) groove.  Other Fords and Mercury cars had a similar pulley but with a larger outer groove.   

It has been chemically stripped and zinc plated to deter rust and is ready for paint.