Found some on Bing images and a couple '80 RR's had the decal, a couple did not, for what that's worth. Not many photo's since very few RR's were made (think I saw the number I saw was 469 or something around that) Might be the one's with the decal were originals and the ones without had been repainted(?) Only speculating on all that.....
I don’t think I’ve seen one before (or just not noticed it).
I would take some photos with a ruler placed beside it and send pictures to someone to get reproductions made. One of the forum advertisers, Phoenix Graphix should be able to make a duplicate for you.
BudW
Thanks Bud. This is a reproduction. I had a local graphics guy (now out of business) trace and remake this for me when I painted the car 15 years ago. I resently bought the kit for 80 Road Runner from Phoenix Graphics. The local guy did a fantastic job of remaking the decals. But the ones on the fenders and doors were installed crooked as hell. I will replace all the others and just leave the Plymouth decal as is.