at more than 400,000 pounds and with a length in excess of 80 feet and massive
4,300 horsepower tractive effort, the SD90/43MAC is one of the heaviest, longest,
and most powerful single diesel locomotives in the world. To date, there have
been three production "versions" of the SD90MAC. The SD90/43MAC was
originally designed with a 6,000hp engine in mind, but was fitted with a smaller
and more reliable 4,300hp engine that ended up being kept that way by most railroads,
even though the option to upgrade to the higher horsepower engine was offered
at a later date.