A couple of comments about the P-motors:
When one partially derailed on the Park Ave. Viaduct, the then Master Mechanic W. E. Whitney decided to use his brand-new hydraulic jack system (Hoesch??) to rerail it. The P-motor was so heavy and the steel deck so worn that it started to deform the deck!
On a different occasion, we had a slew of equipment to move DH from the Lower Level to HM Shops on the night DHE train, about 30 cars altogether. Original idea was to make 2 pulls from the Lower Level to Tower U, backing the 1st pull onto the Upper Level lead, double up and go to HM. The engineer (John Potthast or Gerry Smith) said that the P-motor would make the whole pull easily. When assembled, the P-motor was on the hill to Tower U and it simply walked that train right out!
They were originally equipped for MU operation at CUT, but that feature was eliminated before they left Cleveland. AFAIK, a full tonnage train was never assembled either in Cleveland or New York.