Canadian National (CN), which merged with Illinois Central in 1999. In February 2017, NS began a program to convert its SD70s from DC to AC, which will also have a new wide-nose cab, and several other upgrades. They will be designated as SD70ACC. SD70M (1992-2004) The SD70M has a wide nose and a large comfort cab (officially known as the "North American Safety Cab"), allowing crew members to ride more comfortably inside of the locomotive than the older standard cab designs. There are two versions of this cab on SD70Ms: the Phase 1 cab, which was first introduced on the SD60M, and the Phase 2 cab, which is a boxier design similar to the original three-piece windscreen on the SD60M, which is shared with the Phase 2 SD90MAC, SD89MAC, and SD80ACe. The Phase 2 cab has a two-piece windscreen like the Phase 1 windscreen but the design of the nose is more boxy, with a taller square midsection for more headroom. The SD70M is equipped with D90TR DC traction motors and the 710G3B prime mover. They are capable of generating of continuous tractive effort. From mid-2000, the SD70M was produced with SD45-style flared radiators allowing for the larger radiator cores needed for split-cooling. Split-cooling is a feature that separates the coolant circuit for the prime mover and the circuit for the air pumps and turbocharger. There are two versions of this radiator: the older version has two large radiator panels on each side, and the newer version has four square panels on each side. This modification was made in response to the enactment of the United States Environmental Protection Agency's (EPA) Tier 1 environmental regulations. Also the truck was replaced with HTCR-4, instead of HTCR-I on former model. Production of the SD70M ceased in late 2004 as production of the SD70M-2 model began (the EPA's Tier 2 regulations went into effect on 1 January 2005). 1,609 examples of the SD70M model were produced. Purchasers included CSX, New York, Susquehanna & Western (NYSW; part of EMDX order no. 946531), Norfolk Southern and Southern Pacific (SP; now part of the Union Pacific Railroad), but the vast majority were purchased by Union Pacific. In 2000, an order of SD70Ms made history when Union Pacific ordered 1000 units of the model (UP 4000 through UP 4999, inclusive, although 4014 was renumbered 4479 to accommodate Big Boy 4014 in 2019). This order was later extended