RE: McCoy 35
If it helps you out any Kmot, the first McCoy Red Heads came out in 1957 and a variation in 1958. This early .35 had the red head, and it also had the glow plug centered in the head. In 1961 McCoy came out with a improved version and they moved the glow plug so it was off center in the head. In 1966 they did another production change to the engine. I assume they quit making the Red head engines around 1971 when the new Testors Series 21 engines came out.