When the LT&L started to dieselize their road locomotive fleet, they did it with a fistful of MLW RS-1s & -2s; The RS-2’s were purchased early in that production run, so were not quite as reliable as they could have been, and despite the TdM shops doing heroic efforts to keep the 244-equipped fleet on the road, weren’t able to reduce their shop time to acceptable levels.

So in 1966 the railroad decided to rebuild or retire all of their 244-equipped engines. Four of the RS-2s (371, 372, 375 & 377) were rebuilt to either RS-2ms (prime mover upgraded to “250” specs) or RS-251s (prime mover replaced with a 251), one (#376) was converted to a slug, and the remaining two (#373 & #374) were sold to shortlines.

The two RS-2m’s were sold in the 1970s and #375 went to Musée ferrovaire de Parsons Vale in 2024, but the slug & #377 are still on the roster (377 had a generator fire in 1999, sat in the TdM shops deadline for 12 years, then was remanufactured as a RS-250 and is now running on the Allegany County Railroad).

The DL3 fleet has since expanded as the Parsons Vale has picked up (and remanufactured) additional RS-2s; these have all been converted to ILW RS-250s with their DC drivetrains replaced with AC and their Alco prime movers replaced with Cummins QSK50s. Not many of these units have been remanufactured due to the scarcity of surviving RS-2’s that are not already claimed by railroad museums. (The two RSC-250’s only exist because the Terminal de Montréal bought two traded-in units and pressed them into service on the Parsons Vale’s Canadian rail system; a few museums had expressed interest in them, but intended to buy one of them for parts to maintain the other, while the TdM intended to operate both of them.)