The EMD GP30 is a 2,250 hp (1,680 kW) four-axle diesel-electric locomotive built by General Motors Electro-Motive Division of La Grange, Illinois between July 1961 and November 1963.

[3] It was the first so-called "second generation" EMD diesel locomotive, and was produced in response to increased competition by a new entrant, General Electric's U25B, which was released roughly at the same time as the GP30.

The locomotive in which the 16 cylinder, 567D3 would be fitted, was improved along the lines of the U25B; sealed long hood, central air intake, and engineered for easier maintenance access.

The frame and trucks of the GP20 were carried across; the extra equipment for the centralized air system required more space behind the cab, and since the locomotive was not going to be lengthened, extra space was achieved vertically by raising the height of the locomotive, giving room for the central air system, turbocharger and electrical cabinet all behind the cab.

[3][page needed][4] This extra height behind the cab meant that the body style used for previous GP units was not suitable.

Since EMD wanted the new locomotive to be visibly modern and updated, they turned to the GM Automotive Styling Center at Troy, Michigan for help.

[5][page needed] The GP30 successfully countered the GE threat and kept EMD in the dominant position in the North American diesel market.

The sole purchaser of B units (by the mid-1960s generally an outdated concept) was the UP, who kept the practice of running its locomotives in matched sets much longer than others.

The changes included new generators, Dash-2 modular electronic control systems and 567D3 engines upgraded with EMD 645-series power assemblies, rated at 2,300 hp (1,720 kW) and designated 12-645D3.

[citation needed] The Atchison, Topeka and Santa Fe Railway (ATSF) had previously performed a similar upgrade in its own Cleburne, Texas shops, stripping the locomotives down to bare metal and rebuilding with new equipment.

[8] The Chessie System rebuilt its GP30 units into GP30Ms, adding newer components, new traction motors and reducing their power to 2000 hp.

[9] They lasted with CSX into the mid-to-late 1990s, long after Seaboard System GP30s had been sold, retired and scrapped, or turned into road slugs.