No way this ain't a cuplight....check my Gumball album to see what the cuplight looks like.....about the above, I am not sure what it is, but it does remind me of a type of Line Materials fixture......I will ask someone who may actually know!
I'm not quite sure actually but I think it's sometime between '89 and '95 since this video from '89 shows a string of dayburning MVs at around 8:00 or so and a pic of the freeway from '89 still shows the old Powerlite lumes from the '60s. I think the conversions started in the late '70s early '80s though.
By the way......do those you saw have mogul or medium base? Mine is medium which I found a bit odd......