Doing some research on 74 and 75 Cutlass'. Standard 74's, 442s and Hurst Olds had horizontal bars in the grille and turn signals in the front bumper. 74 Cutlass Supremes has slightly taller grilles with closely spaced vertical grilles and turn signals outboard of the grilles in the header panel. 75's had wider spaced vertical grilles with turn signals integrated into them . The 75 Supremes had a different eggcrate type grille with closer spacing. Rear side window treatment varied as well. Most were large triangular windows. Some had smaller rectangular "Landau" windows. Some of the Hurst Pace Car versions had padded vinyl tops which covered the window openings and had a brushed aluminum strip that ran over the roof. may had T-tops as well. 74 tail lights were one rectangle with the Oldsmobile emblem in the middle. 75's split the taillight vertically into two sections.
I just acquired a grey 75 promo that I will have to backdate to a 74 because my Hurst decal set is for a 74.