The P30CH was a six-axle passenger locomotive built by General Electric for Amtrak in 1975 and 1976. Although it was the second diesel locomotive ordered by Amtrak after the EMD SDP40F, it was the first one that had two separate 375 kW diesel generators to provide head end power. So no power of the prime mover got lost for HEP and it didn't always have to run at rated speed to provide power of the right frequency.
Due to their designation P30CH, they got the nickname “Pooch”. Only 25 were built since Amtrak soon decided to only procure four-axle locomotives. Additionally, they were not very popular and had mechanical problems. As early as in the late seventies, a huge number of the type was leased to other operators in California for commuter traffic. Amtrak used them for the last time in 1991.