To scroll back a bit to 08-06 postings about B&M yards in and around Boston, It was pretty much an unmanageable hodgepodge of named yards. The numbering came into force with George Hannauer, B&M president from 1927 until his fatal heart attack at the 1929 Dartmouth-Yale game. He came to the B&M as a rehabilitator of terminal operations -- the Indiana Harbor Belt, for one -- and put in the Yard 7 and 8 humps in an effort to make Boston a fluid operation. At least some of the fill that brought the New Hampshire main over the Valley Tracks came from the leveling of Asylum Hill, original site of McLean Hospital. If you go to the McLean website, there is an old topo showing the hospital and track layout.
There should be B&M employee magazines from that period on file somewhere with greater detail.
"A gray crossover is definitely not company transportation."