All Model A/AA Ford engines were produced at the Rouge foundry in Dearborn , Michigan with the exception of those engines produced in Canada with prefixes of CA, CAQ, CAW, CAR, CAT, CAY, CAU, CAI, CAO, CAP, CAS, and CAD, and those which were produced in Ireland/England with a prefix of AF.
April 1928 CA 3230 to CA 7172
The engine serial numbers used the same “style” of numbers up to the end of January, 1931 when Ford changed the style of three numbers only. Those numbers were 1, 6, and 9. According to the February, 1931 Ford Service Bulletin, Ford did this “to lessen any possibility of outside individuals attempting to change engine numbers”. This numbering change appeared between A4299173 (January 27, 1931) and A4319643 (February 3, 1931).