from the replies so far, it looks possible that is not the correct decal for that year..
looking for some tri-five specific and found this;
https://www.woodyshotrodz.com/AC-win...n-366c-020.htm
Description
This "Air Conditioned" decal is the window decal that told the world you had air conditioning in your classic. A must for any 100 point restoration.
Trust the Tri-Five Experts for all your 1955, 1956 & 1957 Chevy Parts.
my apologies this is the most recent Osborn catalog I have but shouldn't affect the 50's models
in case my pointer looks familiar - it's a broken M2HB firing pin
and I found the same Osborn DC47 decal part number at Classic that matches the same image from the old catalog and other online references..
https://www.classicindustries.com/pr...arts/dc47.html
hope that helps - good luck!