In '68 option 702 provided a no-cost optional full size spare to match the road tires of the car. The Spacesaver was standard. There are dimples in multiple places in the trunk pan supposedly to help the factory welders locate the place to mount the holddown based on full size vs Spacesaver and convert vs coupe.

I thought I had a picture of one I took of an very nice convert but the tire barely shows at the angle I took the picture.