I thought this was somewhere on the forum, but a duplicate entry is better than none.
The coil stamp.
Ford stamped all their coils for a particular year, the same way. A general stamp with part number, voltage, the FOMOCO script label, etc; and a second stamp with the date code that changed weekly.
There was a change from FOMOCO to Autolite, but I don't know when.
Attached are the main stamp, a general view with the "type" style noted and a sample sheet of date codes (ones I needed to make) for code format purposes. The date code format should be: year (a single number); month (a single letter, capitalized, "A" thru "M", no letter "I"): week of the month (a single capital letter, "A" thru "E", with not to many "E's" used); shift (a single capitalized letter, "A", "B" or "C"). You will note those samples are all 64 thru 66 date codes.
Note: The sample sheet is NOT the correct type.
The main stamp was NOT oriented perfectly. It was placed at a slight angle upwards. In other word - don't make it "perfect". The date code stamps on most of the coils I've had were "smudged". They were in the date code "box" but after the first 600 to 1000 a day for a week, the stamp wore out.
You can take the first two attachments to most stamp making shops and get made what you need, a flat main stamp, and a separate date code stamp (you can sell the main stamp, let that buyer get is own date code stamp). I would estimate that $20 to $25 would be more than enough. I've seen this stamping done. The painted coil was carefully rolled on the stamp, allowed to dry (for handling) then the date code applied. Use white epoxy ink.
Jim