Not to throw a wrench in this but mine says retail also and has staggered shocks :huh:
Actually Ritchie, another "Washingtonian" in Spokane also has a M code Mach1 with the 4V and his doesn't have staggered shocks either. Here's his post.
Okay, I have two 71' m code Mach 1's...the car with factory ram air has the staggered shocks and the non ram air car does not. I have pulled fenders and verified vins on both cars. So I can say for sure that all m codes did not get the staggered shock treatment.