Jason I cannot help you with details of anyone who might have served with your grandfather but I have a link that gives some idea of what he was doing in Jan/Aug 1945 during the advance to the Alps. His unit was obviously concerned with bridging and in particular the Bailey bridge. At Capua there was established the British Bailey bridge school open to Americans, which along with the American School at Maddaloni gave instruction on bridging. It could be he went through one of these establishments. The first mention of the 401st is on page 220* and reading on from there gives some idea of what your grandfather was going through.
*See online: US Army in WW2 - The Technical Services - The Corps of Engineers The War Against Germany. (one volume) https://archive.org/details/corpsofengineers00beck
NOTE. You may be interested that the person who created this website Marion Chard has made an excellent video entitled NO BRIDGE TOO FAR. www.nobridgetoofar.com
Colin Hotham WW2 Researcher.