All the sunroofs were supplied by American Sunroof Corporation - ASC (I think that was the name) . . . was started by a German fellow who supplied sunroofs to BMW, Audi, MB, etc. . . ASC still in business to this day !!

My 74 Duster360 was factory sunroof car. In the A bodies anyway, not sure on B E and C, the sunroof and mechanism was bolted up to the roof of the car.

https://americansunroof.com/

Cheers

Mark