Eugene Day served in the 81st Naval Construction Battalion. His service number was 8172672. The battalion served first in Scotland, England and France the went to the Pacific (Hawaii, Okinawa and Guam). He ended serving in the 5th Naval Construction Brigade on Guam. So it appears he was a Seabee.
The above comes from his PA Veterans Bonus Request papers found on Ancestry.com. I can send them to you if you PM me your email address.
For those with Ancestry Access, here:
https://www.ancestry.com/imageviewer...075&pId=952840
and here:
https://www.ancestry.com/imageviewer...075&pId=952840
Some history on the unit:
https://www.history.navy.mil/content.../081%20NCB.pdf
Also found him listed at the Construction Battalion Training Center at Camp Peary from January 31, 1943 (see line 24).
https://www.fold3.com/image/31330399...2672,ii,states
He enter the Navy on January 29, 1943.