EMD GP40X:
This page is dedicated to EMD's model GP40X. EMD built 23 GP40X units for four railroads as well as 1 GP40X test-bed unit which shared little with the rest of the later units.
Domestic Orders:
GP40 test-bed loco:
| Orig. road numbers | model | EMD serial no. | build date | notes |
| EMDX 433A | GP40X | 29877 | 5/1965 | GP35 frame |
GP50 test-bed locos:
| AT&SF 3800 | GP40X | 776008-1 | 6/1978 | master |
| AT&SF 3801 | GP40X | 776009-1 | 6/1978 | remote |
| AT&SF 3802-3809 | GP40X | 776054-1 thru 776054-8 | 4-5/1978 | |
| SOU 7000-7002 | GP40X | 766066-1 thru 766066-3 | 6/1978 | high hood |
| SP 7200-7201 | GP40X | 766016-1 thru 766016-2 | 2/1978 | |
| SP 7230-7231 | GP40X | 766016-3 thru 766016-4 | 2/1978 | |
| UP 9000-9005 | GP40X | 766068-1 thru 766068-6 | 12/1977-3/1978 |