I thought the RDCs had two-speed torque converters. And I thought that, as built, only the inboard axle on each truck was powered. Is this not so?
I rode the LIRR's two RDCs on two fantrips in around 1959 and 1960. One went LIC-Greenport-Mineola-Oyster Bay-MIneola, then down the Garden City Secondary (flagging each crossing) on to the old Central line. Then the crew changed ends and it was back to Jamaica via the Hempstead branch. The other one went Jamaica-LIC via the Main Line, then back to Jamaica via the Montauk Branch, then down to the south shore via the Montauk Viaduct and the Montauk Branch, and out to Montauk, with the return trip via the Central Branch and the Main Line. On the Greenport trip, I remember they went like a bat out of hell. Running westbound through the North Fork, I was standing at the railing by the open baggage door and we barreled through Laurel (which was a very short platform with no facilities) at what MUST have been far above the MAS, raising a whirlwind of dust and papers and junk behind us. It was a Sunday evening and there was no other traffic on the line at that time. There was apparently a tour train parked at Greenport station on the layup track, with an RS-3 (shut down) and about eight P-72s. I remember on the Greenport trip outbound, we passed a Central Islip Hospital train parked on a siding at Ronkonkoma after discharging passengers. It had an F-M C-liner and a mixture of P-72s and American Flyer cars. We had seen that train depart Jamaica before boarding the RDCs at the start of the trip. I was in the 9th grade at the time.
My understanding is, when the NH and B&M standardized their Boston commuter service with RDCs, operating costs were cut in half. The B&O used RDCs for their Daylight Speedliners. They equipped them with reclining seats, and the first car, a sort of modified RDC-2 (baggage-coach), had a small dinette and food service. An RDC sleeping car service was talked about, but never materialized. This equipment, I think, never realized its potential. RDCs could have taken over all off-peak service on the LIRR in diesel territory, requiring fewer locomotives and unpowered cars just to handle the rush hour overflow.
Fairbanks-Morse forever!