identifying a 68 l78 camaro?

[subyman99]

so looks like this may be a pretty rare car? The wheel... by the valve stem is "DF" nothing else, inside where the cap would go on, next to where the lug nut would seat, one hump it says " k 1 8 and nothing else. on another hump inside where the cap would go is "gm b" ** after doing some research..this may be a 67 z28 wheel. Large "DF" and cant find a date to save my life