Well . . . that lower rr quarter "pattern" kind of. matches that on the front of the lh rocker panel trim, so it might well just be "dirt" rather than otherwise. The panel gap issue mentioned on the deck lid could well be the way the light is hitting it, if you look at the gap at the top of the tail light lens area.
No tilt, no cruise, but velour interior with no center console. But tilt wheel wasn't in the mix that first model year. Could be retro'd from a '76 though, on both counts.
ONE thing y'all missed! "360 4bbl". The rh exhaust pipe is hidden in the shadows, but it's there. What THAT means is the 360HO "Non-Catalyst" true dual exhaust engine, which should be verified by a companion sticker on the lh door structure, below the VIN decal. Which makes it a somewhat rare car on that ONE item. Being a '75 car, it also means that the rear sway bar is there, rather than de-contented as it was, in later years. When that car was new, those were BIG things, to me, especially the HO engine (even it it wasn't a 400HO!) AND things which most dealers didn't have in their normal stock (by observation) as they were "optional" (the particular engine).
Enjoy!
CBODY67