220 -- the class B1x test locomotive
14 powered axles, 7800 hp, ~375 tons, and ~1060 kN of tractive effort for optimal drawbar snapping fun.
This machine teeters on the edge of Big Liz (the PRR FF-1) territory, so the experiment was not repeated.
(EDIT: Added some apropos graffiti)
(The class B1 drawing is cut and pasted from profiles (NYC T-3, Milw EF-1, PRR DD-1) that were drawn by Joshua Moldover @ The Railroad Paint Shop)