The EMD SDP45 was a good passenger locomotive, but to the Santa Fe Railway it did not look the part. EMD therefore designed a lightweight "cowl" body to cover the locomotive, though it did not, as in earlier cab units, provide any structural strength, which remained in the frame. The cowl provided sleeker looks, better aerodynamics at speed, and allowed the crew to enter the engine compartment en route for diagnostics and maintenance. Final drive gear ratio for passenger service was 57:20.
Orders
Santa Fe purchased nine of the locomotives, and the Milwaukee Road bought five for its passenger service. The Milwaukee Road units were delivered without Dynamic Braking. Reportedly, Illinois Central Railroad was considering an order for five FP45s as well, but canceled it. Such low production was feasible and profitable for EMD since the locomotive was fundamentally just a re-clothed SDP45. Power, as in the SDP45, was from a V20645E3 engine developing.
Liveries
The locomotives were delivered painted in the Santa Fe's famous Warbonnet colors, in exactly the same style as the railroad's F units and GE U30CG. When Amtrak took over passenger service, the FP45s were reassigned to fast freight service, particularly Santa Fe's Super C high-speed intermodal run. Seven units were repainted from their original red and silver Warbonnet scheme to the standard blue and yellow freight scheme, while two units were painted into the blue and yellow warbonnet. Their steam generators were removed. Gearing was changed from 57:20 passenger gearing to 59:18 for freight service and they were permanently assigned to the freight pool. All Santa Fe SDFP45s except for #5995 were repainted in the Southern Pacific Santa Fe merger paint and then repainted in the blue and yellow warbonnet scheme after the merger denial. In June 1989, two of the units, #5992 and #5998, were repainted once more in a modified version of the Warbonnet scheme and re-designated as #101 and #102. The units reentered service on July 4 as part of the new "Super Fleet" — the first Santa Fe units to be so decorated for freight service. The six remaining units were thereafter similarly repainted and renumbered to 100-107. In 1990 with the purchase of the EMD GP60Ms the units were renumbered back in to the 5990s and were then renumbered again to 90-93 and 95-98 and remained in the Warbonnet scheme until their retirement in the late 1990s, after some 30 years of service. The units purchased by the Milwaukee Road were painted to the Milwaukee's orange and black scheme after Amtrak took over passenger service.
Between April 1980 and December 1982, Santa Fe's San Bernardino shops rebuilt eight FP45s 5940-5943, 5945-5948. They emerged as 5990-5993, 5995-5998, and were redesignated SDFP45s. The 5944 was wreck retired in September 1981 on account of a wreck at Toland, Texas. Electrically they were upgraded to SD45-2 standards. Mechanically, they were re-geared from 59:18 to 60:17, reducing their top speed from 89 to 83 mph. In the mid 1980s Santa Fe again re-geared them - this time to 62:15 for 71 mph.
Withdrawal
Milwaukee Road's FP45s were all sold for scrap in 1981 and 1984. One of Santa Fe's SDFP45 No. 96 was wrecked in 1994 on Cajon Pass. While No. 91 was sold to the Wisconsin Central in January 1995, becoming their #6652 and the rest stayed in service right up until the BNSF merger in 1996, and were retired shortly after the merger.
Preservation
Those that were not wrecked in service, or sold to other railroads, are on display in museums:
Santa Fe 90: was donated to the Oklahoma Railway Museum in Oklahoma City in a non-operational state. #90 was the last FP45 donated by the Santa Fe and had resided on a RIP track for two years before being delivered to the museum.
Santa Fe 108: was donated in operating condition minus the cab's air conditioner to the Southern California Railway Museum at Perris, California. This locomotive has the distinction of being the last passenger locomotive ever purchased by Santa Fe. Its restoration was completed in October, 2018 and it is now in operating condition for the first time since 2012.
