I think 1952 (QD-13) was the first year to use the split gearcase shared with the 53/54 Evinrude Super Fastwin 15hp. Prior to that the QD used a different gearcase which had ball bearings. The later split case used bushings. The QD-13 also uses teh universal magneto. I’m not sure if that is the first or second year of that so I’m not sure if that is shared with teh QD-12 or not. Someone will correct me if I am off by a year. The QD-12 is the only early QD that I do not have in my collection. I have a 10, 11, 13, 14, 15 and 16 so I’m not as sure about the 12’s particulars.
-Ben