One article I have says 72,455 Mach1's, another says 72,458
Mach1's were produced in '69. Nothing I have in print shows the breakdown between 351's and the three versions of the 428. I have 852 or 858 Boss 429's made and 1,628 or 1,934 Boss 302's made in '69. As you can see it's hard to tell for sure, different books quote different figures.