I think my 1979 silver anniversary trans am has a similar light
I will go back and check soon.
and I may have an extra
just so unorganized mite take a while to find.
I think it is a lamp used by GM on several models.
looks the same
although I looked in one garage at the 79 trans am and a 1987 SS one Carlo hard top has same dome light
Then walked into main shop and looked at the 88 wagoneer..I could have missed a detail or two,....
( the one that is chrome, has two spot lamps for reading and one center dome with milky white lens )
I know GW's also had a square/rect. lamp in rear cargo area that is different.