Rick - This Old GMC Trucks Pickup Serial Number decoding web page helps break down your "EC" code. It shows 1941-46 GMC Pickups used "CC" and 1946 also identified with "EC".

The Old GMC Trucks web site hasn't been added to/updated in quite some time, but still has a ton of great info that might also help with your project too. wink

~ Dan
1951 Chevy 3 window 3100
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"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)