2370 was built in 4/1984 as MKT 371 as part of a 20-unit order of GP39-2s that were produced after normal GP39-2 production had ended and subsequently, these units were built with parts from the GP49 production that was taking place at the same time. MKT 360-379 were renumbered to UP 2359-2378 between 1989-1990, with MKT 371 being renumbered to UP 2370 on 9/29/89. This group of 20 was assigned a new number series in 12/1999, UP 1209-1228. UP 2359-UP 2366 were renumbered to UP 1209-1216 and are still active as such today. UP 2367-2378 (12 units) were returned to their owner/lessor upon expiration of their lease on 7/25/2000. All 12 units were renumbered as temporary WP units in late 2000 and April and May 2001 to clear their UP 2360 series numbers for use on renumbered SD60Ms.