I believe I recall that MM issue also. Even 10 years ago, I thougt that 350,000 64 1/2-66 Mustangs remaining was on the high side. After 40 years, I would bet that there are only around 10% of these vehicles remaining. As fun as these cars are, they were never built, nor driven, to last 40+ years. How many were wrecked, rusted apart and stripped for parts over the years? Correct me if I am wrong, but didn't the 2 millionth mustang rolled off the assembly line in 1967? If that is correct, and we go with my assumption of 10% remaining, you would be looking at less than 200,000 of the 64 1/2 through 67 mustangs surviving today. But the, how many of them are driveable?
Oh, I almost forgot to add... I own one 64 1/2 coupe!