OK, here's my educated speculation.
A perusal of the Fallen Flags L&N drawings, (known to have errors, BTW) shows the units as weighing only 230,000 lbs., compared to some of the other L&N GP-7s with weights ranging from 244,000 to 252,000 pounds. The GP-7L had only 800 gallons of fuel, while the other GP-7s carried 1100 gallons. I don't have a list of weights available at the computer right now, but I imagine a switcher truck would weigh less than a Blomberg. They cost less, just ask the NKP.
All of the above points to a unit built as a lightweight, to be used on lighter rail. The fact that the units were built with friction bearings and schedule 6-BL brakes may support the idea that the GP-7Ls were considered as switchers, but also may have been a cost savings as well; friction and 6 air was cheaper than rollers and 24RL.
I'll go with the idea of road power for some less-than-mainline track. Does anyone really know for sure?
