There are two types of clutch screw drives:
Type A and type G.
Type A, the original design, also known as a standard
clutch head, it resembles a bow tie with a round center.
These were common in GM automobiles, trucks and buses
of the 1940s and 1950s.
Type G resembles a butterfly. This type of screw head is
commonly used in the manufacture of mobile homes and
recreational vehicles and is the type that are being
marketed to us from the vendors today. I don't know
anyone who makes or sells the Type A now a days.
Your '48 would have had Clutch head screws as shown in
the links above.
DG
