GO Transit 600-656
GO Transit 600-656 are MPI MP40PH-3C's. The first order (MPI order 2901-2927), 600-626, were built in 2007 and 2008, and are to date the largest single order of motive power purchased by GO Transit. The second order (MPI order 2109-01 to -20) is numbered 627-646, and was ordered in the middle of 2008. A third order for 10 units (MPI order 2109-21 to -30), numbered 647-656 was delivered by early 2011.
At their July 2008 board meeting, GO's board of directors approved an additional order for 20 units from MPI. While details were not released, it was assumed that they would be more MP40PH-3C's, and numbered above the first 27. The order, indeed for more MP40PH-3Cs, began delivery late 2009 and continued into July 2010 as expected. GO's board at their March 2009 meeting authorized the taking of an option for 10 more units.
Powered by a 4000hp 16-cylinder EMD 710G3B-EFI-T2 and equipped with a 1000hp Caterpiller C27-ACERT HEP package, the MP40PH-3C's are the first locomotives ordered by GO able to supply power to a 12-car train by themselves. They are also faster, being geared for a maximum of 93mph. This series is equipped with 1,850 US gallon fuel tanks.
They are also equipped with a 2-setting HEP system, capable of providing GO's standard 575vAC on either a single of the two HEP buses or on both.
Units are delivered via Union Pacific to Canada, where they are interchanged with Canadian Pacific and sent east to Toronto. All units are transported under MPEX reporting marks until on GO property and in service.
The Georgetown South Project will allow for more traffic along the Georgetown Corridor as well as the Air Rail Link in 2015. GO Transit conducted an environmental assessment on electrification, however identified it would not happen until the late 2010s. It was found that using Tier 4 compliant locomotives would sufficiently mitigate health effects from emissions. GO Transit will have one MP40 locomotive converted to use a Cummins QSK95 Tier 4 engine and act as a prototype to test in 2012/2013. Ten more MP40 locomotives will be converted in time for use in 2015. A request for proposals closed in June 2011 for the prototype. It was later announced that dual Cummins QSK-60 diesel engines would be substituted for the single QSK-95. 
The first order of units is equipped with GO's usual Nathan Airchime K5LA 5-chime horns, however horns on the later orders are the K5LLA with a different #1 bell, resulting in a slightly different sound.
|Fleet numbers||Build date||Serial numbers|
|600-626||2006-2008||2405-01 to -27|
|627-646||2009-2010||0308-01 to -20|
|647-656[Note 1]||2010-11||0308-21 to -30|
- ↑ 647-656 exercised option for 10 more units on second order.
- ↑ Cummins to produce Tier 4 compliant diesel engine Railway Gazette. 2 November 2011 (Sutton). Retrieved on 2011-12-18
- ↑ Georgetown South Project: Human Health Mitigation Plan Feedback – June 2 to July 4, 2011, gotransit.com, retrieved on 2011-12-18
- ↑ MotivePower to repower Metrolinx locomotives with new engines railway-technology.com. 16 August 2012. Retrieved on 2012-11-27