Lazste - Below is a screenshot from the GM Heritage Center documents (same picture and measurements for 3800 pickup bed for 1954 & 1955.1) that can help confirm your parts. These are "Inside" dimensions. If your bed side panels measure over 105" long, they are definitely for the 3800 and 9' bed.
~ 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)
