In the second panel Happy says "Beck gets the Purple Heart, Eppy the Silver Star..." Referencing artists Joe Beck and Otto Eppers, who may very well be caricatured in this panel as well. See a photo of Otto Eppers here:
http://www.arrl.org/images/view/AWE/Clark/otto_cropped.jpg
Signed in panel 3. Bails' Who's Who lists "Braeburn" (no first name) as a shop artist for Chesler.