I had same problem with my '46, used a '49 Chev passenger car's front license plate guard and made it fit my rear bumper. This item is available from vendors like Chevs of 40s etc and show up at swap meets.
I'll try to pm a photo for you.
Best of luck

Last edited by cletis; 03/30/2017 12:40 AM. Reason: deleted Ebay link
It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed