Erie-Lackanna, Delaware & Hudson and Boston & Maine pooled power on piggyback trains PB-99 and PB-100, Chicago to Boston in the late 1960s. The basis was horsepower hours and the usual assignment was EL power 2 days, D & H 1 day and the rest, 3 or 4 days B & M. B & M power was puny, usually GP-9s, sometimes a GP-18. EL units were SD-45s(?), 3600 series, I think. During the week PB-99 was run right at the tail end of the evening rush hour, right behind Boston-Ayer RDC train #629 (5:53pm out of North Station) via Waltham and Concord. He always put on a good show. More than once, I saw PB-99 at Hill Crossing, waiting for #629 to pass.
The schedule was about 5 hr. 15 min. to Boston-Mechanicville; there were already some extensive single track sections. Picked up Worcester and Holyoke trailers at East Deerfield. Dropped milk - that's right 3 milk cars - at HP Hood in Eagle Bridge.
Someone didn't tie down D & H units one time at the old Boston Engine Terminal and they knocked out part of a back wall.