The GE B23-7 is a diesel locomotive model that was first offered by GE in late 1977. Featuring a smaller 12 cylinder version of the FDL engine, it is the successor to GE's U23B produced from early 1968 to mid 1977, but at long is exactly . longer. It competed with the very successful EMD GP38-2. General Electric also produced a variant, the BQ23-7, No. 5130-5139, for the Seaboard Coast Line. A total of 536 B23-7's were built for 9 U.S. customers and 2 Mexican customers.
A B23-7A is a 12-cylinder B23-7 with horsepower boosted to 250 per cylinder or 3,000 horsepower. In 1980 the Missouri Pacific ordered three B23-7A's (#'s 4667–4669, later UP #'s 257–259) and tested them system-wide. The result was the GE model B30-7A, B30-7 with a 12-cylinder FDL prime mover. They were not renumbered into the B30-7A series on the MP because they lacked Sentry Wheel Slip and had different engine governors.
13 B23-7's were built by GE of Brazil in Dec.1979 for United South Eastern Railways(FUS) no.522-524 and National Railways of Mexico(NdeM) no.9130-9139. 17 B23-7s were built from GE kits in Mexico as Ferrocarriles Nacionales de México no.10047-10052 and no.12001-12011.
Southern Railway's 54 units had Southern's "standard" high-short-hoods.
Preservation
Ohio Central #4092, a B23-S7 "Super Seven," is owned by the Age of Steam Roundhouse in Sugarcreek, Ohio. It was rebuilt from former Western Pacific U23B #2252.
Original owners
{| class="wikitable"
! Owner
! Quantity
! Numbers
! Notes
|- align = "center"
|Atchison, Topeka and Santa Fe Railway
|69
|6350-6418
|6405-6418 last B23-7s built
Transferred to BNSF
|- align = "center"
|Conrail
|141
|1900-2023, 2800–2816
|2800-2816 first B23-7s built
Three sold to Metro-North, others split between CSX & NS.
|- align="center"
|Ferrocaril Unidos del Sureste
|3
|522- 524
|
|- align="center"
|Louisville and Nashville Railroad (Family Lines)
|15
|5115-5129
|Transferred to CSX
|- align="center"
|Missouri Pacific Railroad
|85
|2289-2338, 4650–4684
|2289-2338 renumbered to 4600–4649
Transferred To Union Pacific
|- align="center"
|Ferrocarriles Nacionales de México
|122
|1-01-1-08, 9130–9180, 10001–10052, 12000–12011
|
|- align="center"
|Providence and Worcester
|1
|2201
|Transferred to Railroad Museum of New England for parts
|- align="center"
|Seaboard Coast Line Railroad (Family Lines)
|29
|5100-5114, 5130-5139 (BQ23-7), 5140–5153
|
|- align="center"
|Southern Railway
|54
|3970-4023
|High Hoods. Transferred to NS
|- align="center"
|Southern Pacific Railroad
|15
|5100-5114
|
|- align="center"
|Texas Utilities
|2
|3306–3307
|
|- align = "center"
|}