Same here, in exactly what manual were your looking? I’ve got a 1946-72 ½ thru 1 ton truck, series 10-20-30 GM Parts Catalog and I looked in groups 3.900 thru 3.935 and didn’t see any cap screw with a hole in it mentioned. Also looked in the 1955 and 1959-60 shop manuals and again, no mention of a hollow bolt or with a hole in it.
DG
