The long-awaited EMD 265H 6,000 horsepower engine finally made its debut in September 1996. The SD90MAC-H can be identified by dual exhaust stacks of the twin-turbo 265H engine, and beveled edges on the hood over the engine compartment. Pre-production units spent time in Colorado doing some high-altitude testing on Union Pacific’s Moffat Tunnel Subdivision and a stint at the AARs Transportation Test Center in Pueblo. Here, UP SD90MAC-H No. 8503 (along with 8502, 8505 and 8504), are being put through the paces at Plainview on February 3, 1998.
