Gabor, the 2 "1"s were different thicknesses too; if you go down to the last page on the second link there are 2 shots of 73, the same plane in both as the radio serial is the same (if you enlarge the second photo I think you can see a slight shadow under the 73). Obviously taken later with weathering. In the 100FS the c/o flew no "1"; Turner replaced Capt. Robert Tresville who was lost in the sea 22 June 44 in P-47D 42-75798 (MACR 6079) at the time the Group was converting to P-51s. He is remembered on the Sicily-Rome Memorial.
No luck with 73's serial though.
https://www.facebook.com/permalink.p...d=121277570085
https://timelessmoon.getarchive.net/...rmy+air+forces
Nick