Might be 1/2-11, or 5/8-13, readily available at hardware store.
Ed
I think you may have that backwards Ed. 1/2”-13 or 5/8”-11
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum