As part of the D&H South electrification scheme the Portland Shops designed an express motor to run freight at 110+ MPH (class 6 trackage for 110mph/177kph, and some Canadian trackage that was temporarily waivered for 150mph/250kph.)

The solitary class L – #799 – is what came out of it; a motor that drew on 5 years of testing of regeared class E & K motors, actually capable of pulling (short) freights at 150mph without catastrophe.

One big change from the class K design that was settled on was to equip it with a set of trucks outfitted with passive radial steering and to give it a pilot truck (also passively steered) to equalize the weight on the powered drivers & deal with a terrifying shimmy that occurred at speeds over 120mph; that plus the appropriately huge AC transformer it needed for operation on D&H South stretched the carbody out to an unheard of 71'6" – a hair longer than the EMD E9’s that had until fairly recently held down commuter service on the Burlington Northern out of Chicago.

Alas, Amtrak balked at the idea of running super-fast freights on the NE Corridor, so 799 was the only unit of this class built.

It has been regeared for 120mph, and remains in service as a freight motor.