When the PV&T decided to electrify in 1911, they started by putting up wire on the Brattleboro subdivision (Merrimack to Brattleboro) and ordering a pair of prototype units to test on this line; this one – X1, because it arrived first – from GE and another – #X2 – from Westinghouse. The two spent the first 6 months of 1912 (they arrived early in January) being evaluated in freight & passenger service, and ended up being rated very closely together with only one thing the operating department considered disqualifying.

X1 had the advantage of being able to run on curvier track (the PV&T had some idea that they could use streetcar curves on industrial trackage instead of having to engineer around traditional railroad curvature), and had more tractive effort due to having power to all wheels, but had less horsepower and so couldn’t maintain passenger schedules on all but the smallest trains (not actually a problem, because the railroad planned to keep using steam to pull the passenger trains to avoid switching delays). X2 was faster, considerably more powerful, but was lighter and couldn’t navigate the tightest curves on industrial trackage.

The one disqualifying flaw that X2 had was that it was too powerful and fast for the curvier sections of the PV&T mainline, so X1 was picked as the prototype for another 11 motors with only a few small changes to the design (moving the doors closer to the center of the unit and putting dedicated windows in for the driver & stoker.

X1 – now reclassified as class A and renumbered to #201 – remains in service today more than 100 years since it was delivered.