Engine Date Code Clarification

  • The Date code on my 1965 K code is "24 R". Could someone please help me clarify which engine date code or codes for my block and heads would be most acceptable ( A, B, Q, or R) ? Thank you for your input.

  • I assume you are referring to the scheduled build date of your car, which is designated by the DATE code on your warranty plate. What you need to understand is that Ford had to go to 2nd year month codes since the Mustang was introduced mid-year 1964 and as a 1965 model. 24R would decode to April 24, 1965. Your engine casting dates and pretty much all other date codes throughout the car would <b>not</b> have followed the 'R' month code for April. Instead, the normal 'D' month code would be applicable and prior months as expected.


    So, to answer your question, your engine casting dates would most likely span from as early as January/February (5A, 5B), through March/April (5C, 5D).

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    I have 2 separate date code books and I see what you are referring to. I currently have a date coded block "5C". When I look in the decoding books, I interpret this as a 1964 not a 1965 and this is where I am confused. Should I be looking at the list which says first year or second year. Second year doesn't show a C, it shows A, B, Q then R. Thanks for your assistance.


    Edited by - ccs on 03/21/2010 19:42:08

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    Edited by - ccs on 03/21/2010 19:46:08

  • CCS,


    I have an April "build date" K 2+2 from Dearborn - mid April - 12R.


    My engine is original and VIN stamped. All of my engine castings are EARLY March '65. 5C1 intake, 5C7 block, 5C9 heads - if my brain is working correctly.


    You will need 5CXX type datecodes on your castings.


    Ford started '65 Mustang "CAR" Build dates back in early '64 - that is why our car build dates are "R" - because Ford kept using VIN numbers and build letters well beyond the normal 12 month period since they considered all cars "1965" cars even built in early '64 - so the CAR build dates DO NOT follow the normal Ford datecode format for month letter in '65.


    However "CASTING" dates and individual part datecodes were still subject to Ford's normal datecode formats.


    An April '65 built Mustang will have a xxR build date, but have part and casting datecodes in the 5A, 5B, 5C, and possibly 5D ranges. My car even has a few parts well before that - like the tranny case and tailshaft - late '64 castings - but a VIN stamped case.


    I hope this helps.


    Edited by - RalphJr on 03/22/2010 07:52:18

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