what was the first year for the space duster?

No, it was a separate option. I have had cars with just the fold down back seat and presently have two 360 Dart Sports with the fold down back seats and sunroof. I have NEVER seen a sunroof car without the fold down back seat, though. Of course, there were the Swinger with the sunroof but cannot have fold down back seat. I'd like someday to have my cars decoded by Galen to see how many cars actually came with sunroofs. I don't think there were many.

I've had my #'s matching 73 340 Dart Sport "convertriple" decoded and documented by Galen Govier. He does not have a #'s breakdown for the M52, C73 options, combined or seperately, be it a 340, 360 car, ect. My guesstimate is the percentage is low for 340 and 360 cars with these options.

I have also been told that G.G. says all M52 crank sunroof A-bodies came with a white headliner regardless of interior color. NOT! My headliner is the original in excellent shape, never altered in any way shape or form, and guess what? It's Black.