Hi Pieter
Is this the part?
If I've got what you are looking for correct you need the special bolt that the hand brake actually pivots on. In the HUP parts book calls it Fulcrum, Hand Brake Lever, it is group part number 4.613 part number 601142 (before vehicle Serial No. 384--14502) the 601142 number crosses over to basically all Chevy civilian trucks 1938-1947.
The 601142 is both Canadian and US Chevy part number, US parts book adds the following information (7/16-20 x 2/18 w/ 5/8 dia.)
The after HUP vehicle Serial No. 384--14502 part number 5819126 does not cross over to civilian Chevy Trucks.
Hope this helps