Bill - I don't have access to the physical part to measure, but some research through GMC Master Parts Books and military part numbers/specification listings revealed that I believe that the diameter of the flow restricting hole in the fitting diameter should be 0.078".
See the screenshots from the resources I found below. Hope this helps.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
