I am trying to bring up some information for you in response to your inquiry regarding the 91st. OBDS, but only draw blanks.
I assumed that this was a part of the 91st Infantry Division, perhaps a combat engineer unit, but found that the combat history for that division did not match the campaigns you listed.
Then I reviewed all Infantry Divisions, and again came up blank, so at this point I am clueless.
I'd like to have a look at his separation papers, if available, which are not the same as his Discharge,which I's like to see too. I may glean something which could get me off dead center. Without charge, of course.
My Fax number is (817-292-0249, or mail to 3712 Wayland Drive, Ft. Worth, TX 76133.