John - My resource info shows the following for your two pictured intake manifolds. They both are listed under the same GM PN: 3835587.
Casting# 3835590 (w/tab) 1948-56 235
Casting# 3754844 (no tab) 1958-62 235
~ 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)
