In 83 and 84 you only got two colors, blue or white. AND......no factory sunroofs on G-body Monte SS. Why? Probably because of bench seats.
I don't know. Monte options were strange. Back in '83, it's not like people were falling all over themselves to get into a Monte SS. Nice cars, but they were rather subdued. I never talked to anyone saying "I'm going to go get me a new 83 Monte SS."
This 83 better be a labor of love to get that puppy back up and on the road safe. I'd pass on it myself. And it's not like it's an Aero coupe or something worth a couple of dollars more. You'd have tons invested in metal work/parts/labor getting that puppy just basically ready for paint (doing it right) and for what? Peel back that layer and I'll bet there's more in that story as to where all the rust is. If that's something that someone sees as a challenge...then go for it. Otherwise, drop the wrench and back away slowly.