Division & Regimental Insignia
My error. 20th Infantry was assigned to 6th Infantry Division until inactivated in 1949.
If you're certain, you'll want a shoulder sleeve insigne (shoulder patch) of the 40th Infantry Division and one of the 6th Infantry Division. The distinctive insigne of the 20th Infantry Regiment is a small metal (brass) crest inlaid with enamel. This would cost $12 if I can find one. I'll let you know what I can come up with. If you can determine what regiment of the 40th Infantry Division he served with I'll try to locate a crest of that regiment also. This will have been the 108th, 160th or 185th Infantry.