Posted this collection of pictures over on another forum and thought they might benefit some here
First (after use of generators) version with the round rear case So 1965 to Nov-Dec 1966 ( almost to mid 67 production)
Second version - around Dec 66 to May or so 68
Third version - May or so 68 to 71 or 72 haven't narrowed down the month
The next version carried a MOTORCRAFT cast in the rear case as AUTOLITE was