Cars were such junk back then I could see rust like that happening within ~6 years or so.
The picture I present y'all is cropped, there are uncles and girlfriends/wives also present, if I had to have a definitive date. Am mostly trying to figure out what junk my Dad kept in his fleet, he doesn't talk much about that era. Neither myself nor my eldest cousin are in the pic, so we're either off camera (A pic of "the boys") or it's before 1975.
He did have 67 and 69 Mustang convertibles, the carburetor on the 69 mustang had a really stiff spring for some reason so the gas pedal was real hard to push down, my Mom hated driving that. Nevertheless, those cars did not make him any cooler.
He drove used Ford wagons through the 70's then bought a new Fairmont in 1980... Factory ordered with the inline 6 and 4 speed manual transmission... never another like it, I'm sure.