https://www.findagrave.com/memorial/100775371/stephen-e-o'brien
https://www.fold3.com/image/291536760
https://www.ourfamtree.org/obituaries/view.php/Donald-R-Perkins/id/4863
http://www.veteransofthebattleofthebulge.org/vbob/wp-content/uploads/2011/03/1999-May.pdf
As you've probably already noticed, there's not a lot of online info on this unit, therefore I suggest that you contact the following:
NARA in Maryland - they have unit records and you can even hire a research assistant (as I did)
Contact the Engineer Office of History in Alexandria VA - they were instrumental in my research - you can call too - 703-428-6563
Fort Leonard Wood - Office of Engineer History
Historian, U.S. Army Engineer School
320 MANSCEN Loop, Suite 043
Ft. Leonard Wood, MO 65473
573-563-6365
or
https://www.eisenhower.archives.gov/research/conducting_research.html
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"