1974 Duster 360 with sunroof production numbers

"Space Duster" option was actually pretty popular.

Also for some reason, 1974 was a very popular year for sunroof cars.

There should be a percentage breakdown for Dusters in general with the sunroof and/or Space Duster option, and while there are other factors like- "most people who wanted a 360 and a four speed did NOT want a sunroof" mentality, you can kind of extrapolate/interpolate that percentage applied to the production figures for 360 4 speed cars.

Not perfect by any means, but that's what there is to work with.

EDIT- I guess I was thinking about the "Convertriple" package vs Space Duster, which IIRC was only the fold down seat.