The model years of 1978, 1979, and 1980 were transition years for GM.
In 1978, the A body (Cutlass) was downsized, following the latest trend
for American auto-makers. Contrary to some other information, the
Cutlass line, according to GM's own documents, was still an A body until
1981 when it became the G body. The A body in these years though, had
more in common with these later G bodies than the traditional A body.
I say these years are "forgotten" because they are currently, popularity
wise, the underdog of Cutlasses... occupying essentially the same spot
that the early 70's Cutlasses held in the last few years. As the owner
of a 1979 Cutlass Supreme, it gives me hope for my own year, that these
other underdogs are finally getting their deserved attention.