Welcome to the Forum,Gilbert-and include Portland Termnal Co. HH-660s along with the MEC/BM units. P.T.C.O. did the switching in the Portland Maine area for those railroads. There is a fairly new paperback on Boston & Maine switchers that has photos,and really,any of the books on the B&M and MEC that have a lot of photos. There is also the out of print small paperback by Ed Robinson,"Maine Central Diesel Locomotives"(also includes P.T.C.O.) that has some photos,rosters, and dimensions & plans. Bud