I think they were standard equipment in 1978. I say this because I used to have a 1977 Dodge Monaco CHP Police car and wanted to put the cop car wheels on it,and a purist in Police car restoration told me that was a "NO-NO" because they didnt come standard until 1978.

EDIT: Maybe im confused,It was either the wheels or the Police Car Dog Dish caps that didnt come into play until 1978,cant remember which I was told.