This proved to be more efficient than the car body design as the hood unit cost less to build, was cheaper and easier to maintain, and had much better front and rear visibility for switching.

ALCO, Fairbanks-Morse, and Baldwin had all introduced road switchers before EMD, whose first attempt at the road-switcher, the BL2 was unsuccessful in the market, selling only 58 units in the 14 months it was in production.

[7] Its replacement, the GP7, swapped the truss-framed stressed car body for an un-stressed body on a frame made from flat, formed and rolled structural steel members and steel forgings welded into a single structure (a "weldment"), a basic design which is still being employed today.

The GP7 proved very popular, and EMD was barely able to meet demand, even after opening a second assembly plant at Cleveland, Ohio.

[citation needed] The "GP" designation stood for "general purpose", while the "7" had no meaning other than matching the EMD F7 cab unit then in production.

Two control stands for either direction running was also an option, but one end would still be designated as the front for maintenance purposes.

[13] All but the first locomotive rebuilt had their front (short) hood reduced in height for improved crew visibility.

In 1960 the Alaska Railroad purchased a dozen GP7Ls from the US Army and rebuilt eleven of them in 1965 with low short hoods for better visual clearance.

Canadian Pacific Railway rebuilt their GP7 fleet in the early 1980's as GP7u units for yard service, including a chopped short hood, new numberboards and front cab windows, and upgrading the 567B prime movers with 645 power assemblies and to "BC" engine block specs (some upgraded with 567C engine blocks out of retired F-units).