Hey Bill,
I can't tell you what ever happened to clutch head screws. There were a few, or least a couple, different "types" as far as I know. For some reason, I have it in my mind that clutch head screws were frequently used to assemble tow-behind campers and mobile homes back in the 1950s and 1960s. They may also have been used on similar vintage car interiors, like dashboards, upholstery, etc. I posted the "G" type screwdrivers offered by Sears/Craftsman back on page 9, reply 134. I included them below as well as the three type "A" clutch head screwdrivers also offered by Sears/Craftsman during the same time period. The catalog page is from the 1960 Craftsman Hand Tool Catalog. (Notice both of the smallest screwdrivers from each type still retain their original price tags, which read $1.29..... same as the catalog.) Sears/Craftsman also offered three Type "A" 1/4" drive socket bits. Funny, but I don't think Sears ever offered type "G" socket bits. Again, the catalog reference is from the 1960 Craftsman Hand Tool Catalog.
Jim C.