I checked for a 1473 EM Co alumni association to no avail.
I did locate contact information for a 1476 EM Co and a 1478
Ken please advise if you want this contact info as like units sometimes have knowledge of other closely numbered outfits.You could give them a call and see if they can add any information to your quest?
Also where is the home of the US Army Engineers.Is it now the Corps of Engineers? Most Army branches have historical units that might also be of help.