The AC6000CW was designed at the height of a horsepower race between the two major locomotive manufacturers, Electro-Motive Division of La Grange, Illinois, and GE Transportation of Erie, Pennsylvania, in the early to mid 1990s. The goal was. GE worked with Deutz-MWM of Germany in 1994 to design and construct the 7HDL engine for the locomotives. The first locomotive constructed was the "Green Machine" GE 6000, nicknamed for its green paint scheme. The first production models were also built in 1995: CSX Transportation 600-602, and Union Pacific Railroad 7000-7009. After testing was completed by GE, they were released to their respective owners in late 1996. The initial locomotives suffered from various mechanical problems with the most severe being the engine itself. There were major vibration problems which were addressed by increasing the engine mass to lower the resonant frequency. This in turn caused problems with the twin turbochargers. These problems caused GE to push back full production of the new model until 1998. Changes such as stiffer materials and increased engine wall thickness were in place at full production. GE built 106 AC6000CWs for Union Pacific with the older, proven 7FDL engine, rated for. These units were originally supposed to be converted to the 7HDL engine after the problems were worked out with the engine, but this never occurred. GE considers these units as AC6000CW "Convertibles," while UP classifies them as C6044ACs or AC4460CWs. The AC6000CW ended production in 2001, although Union Pacific's 75xx series remains in daily use as of 2010, mostly on rock and gravel trains in Texas. Union Pacific designates these units as C60AC, CSX as CW60AC and CW60AH. CSX Transportation has re-powered many of their AC6000CW units from 16-7HDL engines to GEVO-16 to make them more reliable and environmentally friendly. These units are capable of but are rated at and classified as CW46AH. On June 21, 2001, all eight of the Australian railroad BHP Billiton's GE AC6000s combined to set the world record for the heaviest and longest train. They hauled and 682 wagons for between Yandi mine and Port Hedland. The train was long and carried of iron ore. The record still stands.
*** 6070 Port Hedland scrapped following an accident in May 2011
*** 6071 Chichester
*** 6072 Hesta
*** 6073 Fortescue
*** 6074 Kalgan
*** 6075 Newman
*** 6076 Mount Goldsworthy
*** 6077 Nimingarra
In 2013/14 these were replaced by EMD SD70ACes. Despite their historical significance, they were eventually scrapped in late 2014 after BHP couldn't find any buyers who were interested in acquiring the locomotives.
CSX Transportation:
* 3 units, numbered 600-602, were among the first production AC6000CWs built.
** 601 is lettered "The Spirit of Waycross".
** 602 is lettered "The Spirit of Maryland", and is the only AC6000 on CSX property to retain its original Hi-Ad 6-wheel trucks, which are identical to the trucks of the GE Dash 9-44CW, the GE Dash 9-40C, and the GE ES44DC
* 114 units, numbered 603-699 & 5000-5016, were built between October 1998 & April 2000.
* 600-602 original prime movers replaced with 7FDL16 engines. This is due to these units being pre-production models & mechanical differences between them and the production model.
* 603-699, 5000-5016's original prime movers replaced with 16 cyl. GEVO prime movers and new computer equipment essentially making them ES46ACs. CSX classifies these units as CW46AHs.
*5015 and 5016 were both classified as a CW60AH.
As of April 23, 2018, most of the CSXT C60ACs have been retired and sold to Progress Rail. They have been shipped to Mid-America Car in Kansas City, Mo. Currently, only the 600-602 are still on the roster, the rest having been sold to Progress Rail, Railroad Bull Sheet, and The Diesel Shop.
Progress Rail: Obtained most of the former CSXT C60ACs in April 2018. All were sent to Mid-America Car shop in Kansas City, Missouri and have been patched and re-lettered for PRLX. The locomotives still remain in their "YN2" & "dark future" paint schemes. 616 retains CSXT heritage SAL emblem on nose with PRLX lettering.
Union Pacific
* 10 units, numbered 7500-7509, were built between November 1995 & December 1996. These units were originally numbered 7000-7009.
* 45 units, numbered 7510-7554, were built between July & December 1998.
** 7511 suffered an electrical fire and was retired from the roster in June 1999. The damage was covered under warranty and the unit was sent to GE for repairs. GE built another 7511 unit for UP to replace the original in January 2001, renaming the original 7511 to GECX 6002.
* 25 units, numbered 7555-7579, were built in January 2001.
* All were converted to AC4460CW units and renumbered to 6888-6968.
Union Pacific Convertibles:
* 70 units, numbered 7336-7405, were built between November 1995 & September 1996. These units were renumbered to 7010-7079 to make room for ES44ACs.
* 42 units, numbered 7300-7337, 7339, 7340, 7342, and 7344 were built between March & May 1998.
Beginning in 2018, Union Pacific is sending its AC6000CWs to GE for rebuilding. The rebuilt units are classified as C44ACM.
* 8 units, numbered 6000-6007, were built for the CSX as AC6000CWs, later downgraded to CW46AHs and bought by the WNY&P second-hand from Progress Rail, these units started operating on the WNY&P in 2019.
