You'd have to actually get a Marti report that would tell how many Mach's with that engine code (unless they all were)
1973 Mustangs were the last of a famous generation of Mustangs. The high-performance engines were already becoming less available. And it just so happened that the convertibles were also becoming an "endangered species" of Mustang. After `73, the Mustang wouldn't see another convertible. Convertibles returned nine years after there deletion, in 1983.
PRODUCTION NUMBERS Hardtop - 51,480 Fastback (Sportsroof) - 10,820 Convertible - 11,853 Hardtop Grande - 25,274 Fastback (Sportsroof) Mach 1 - 35,440 TOTAL - 134,867