| Owner | Quantity | Numbers | Notes |
| Atlanta and West Point Rail Road | 1 | 733 | to Seaboard System Railroad to CSX |
| Alaska Railroad | 10 | 3000, 3007–3015 | 3000 renumbered to 3006 |
| Baltimore and Ohio Railroad | 218 | 4100–4162, 1977, GM50, 4185–4256, 4287–4311, 4322–4351, 4422–4447 | Chessie System paint to CSX |
| Boston and Maine Railroad | 18 | 300–317 | |
| Chesapeake and Ohio Railway | 95 | 4165–4184, 4267–4281, 4372–4421 | Chessie System paint to CSX |
| Ferrocarril Chihuahua al Pacífico | 29 | 1008–1036 | |
| Conrail | 129 | 3275–3403 | To CSX and Norfolk Southern Railway, |
| Denver and Rio Grande Western Railroad | 37 | 3094–3130 | All to Union Pacific Railroad. |
| U.S. Department of Transportation | 1 | 003 | |
| Detroit, Toledo and Ironton Railroad | 20 | 406–425 | to Grand Trunk Western Railroad 6406–6425. |
| Florida East Coast Railway | 24 | 411–434 | 433–434 were last built |
| Georgia Railroad | 2 | 755–756 | to Seaboard System Railroad to CSX |
| Kansas City Southern Railway | 4 | 796–799 | |
| Louisville and Nashville Railroad | 17 | 6600–6616 | Family Lines Paint, to Seaboard System Railroad to CSX |
| Reading Company | 5 | 3671–3675 | to Conrail |
| Richmond, Fredericksburg and Potomac Railroad | 7 | 141–147 | to CSX |
| St. Louis – San Francisco Railway ("Frisco") | 25 | 750–774 | to Burlington Northern 3040–3064 |
| St. Louis Southwestern Railway ("Cotton Belt") | 56 | 7248–7273, 7628–7657 | |
| Seaboard Coast Line Railroad | 25 | 1636–1656. 6617–6621 | 6617–6621 Family Lines paint; all to Seaboard System Railroad now CSX |
| Ferrocarril Sonora-Baja California | 15 | 2104–2112, 2309–2314 | 2104-2112 have High short hoods w/steam generator for passenger service only GP40-2 built with high short hoods |
| Southern Pacific Transportation Company | 68 | 7240–7247, 7608–7627, 7658–7677, 7940–7959 | |
| Texas, Oklahoma and Eastern Railroad | 3 | D15–D16, D20 | |
| Western Maryland Railway | 35 | 4257–4261,4312–4321, 4352–4371 | Chessie System paint to CSX |
| Western Pacific Railroad | 15 | 3545–3559 | |
| Western Railway of Alabama | 1 | 708 | to Seaboard System Railroad to CSX |
| Total | 861 | | |