Re: '66 Starcraft, My first boat!
Toast--
yes, OMC built both Johnson and Evinrude. for all years relevant to either of us, the motors were identical except for exterior trim and housing shape....ALL mech parts interchange. OMC also made Gales, which were likewise mechnically almost identical to the contemporary Johnnyrudes, but i think stripped down a bit.
get the Sierra Marine catalog.....Sierra is an aftermkt manufacturer of parts for marine engines etc and makes very good stuff qualitywise....they carry lots more for old OMCs than most outfits. i think iBoats sells their stuff. but you will probably have some issues on major parts for a 66....tuneup parts and carb kits should still be available.