Ed - The 1942-47 Chevy Shop Manual, on Page 4-7 gives the guidelines for shims when reinstalling the original ring and pinion or replacing the ring and pinion gears. Below is a snapshot from the book with the details. Hope it's of some help.
~ 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)
