Your choices for original blue colors for 1951 trucks were Windsor Blue and Mariner Blue. See HERE. Painref.com is a good resource. If you click on some of the other codes, you might get a code for the same color for your preferred paint brand. The PPG and Dupont codes usually generate a HUH?? from the paint supplier guys.
Or if you want a local match, like Otto said, find a concealed spot. I found original paint under the gasket for the side mirror arm on the cowl.

[On edit]From poking around on paintref.com, it looks like Trophy blue was a Chevy Car color in 1951. link

Last edited by klhansen; 01/05/2024 1:33 AM.
Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.