In the little town of Colfax, northwest of Eau Claire in Wisconsin is a small rail museum. They have a few interesting old cars, some old magazines, a collection of rail china and lanterns.
And they have a GP30, ex Soo 703. It needs a little love, but it's a GP30 - a classic. Built 1961-63, its 2,250hp engine with associated turbocharger had a distinctive sound in addition to its distinctive carbody. (See here for a short clip of a GP30 idleing.)
This is one of the few GP30s that rode on ALCO trucks (as the result of resuing trade-in equipment). Soo had 22 of the GP30s.
The electrical panel at the rear of the cab. Click for a closeup of the switches.