Beg to differ. It means "Special Order V8". IF someone (say Garlits) wanted a Dart with a 383 2V and the factory felt like building it, it would have had a "M" in the VIN for that motor, cause it would have been a special order V8 in that car. Doesn't matter that a 383 2V could be had in a Satellite. It wasn't available in an "A", so it would have been a "special order V8"