Should we give him a t-shirt for answering a triva question?
Actually there were no convertable Mustangs built from '74 thru '86. From '83 to '86 Cars left the Dearborn Assembly Line as a 2-door notchbacks minus glass, and headliner, and were shipped to Cars and Concepts, in Brighton MI. They would reinforce the floorpan, remove the roof, and install the convertable top.