440 m code block

Well thanks for your input. It holds true to what I have read.my literature states that january 1, was the cutoff. Before that has full vin, after january 1 it has the last 8. But this guy says he has a m code that was built on 03/29/1969 ( same as mine ) and it has full vin. Plus he has had others , and they all had full vin. He maybe playing me ?

M code cars were built over the transition time meaning the early cars may have the 13 digit VIN and the last cars don't. What's important is SPD. Start with that info.