Illinois Central #1, the only 4-6-4 Hudson (at least in North America) that was built for freight service.
The Illinois Central was a notoriously thrifty railroad and loved rebuilding locomotives in their Paducah shops. Whether it was converting old 2-8-2s to 0-8-2 switchers, cutting up 2-10-0s to build 4-8-2s, converting old saturated steam locomotives to superheated or repeatedly overhauling GP-7s and GP-9s and keeping them on the roster until the 1990s, the IC did it all. But the IC was never a tinkerer. Their rebuilds all followed pretty conventional, proven lines of thought. They did not experiment with outlandish or unusual designs like the PRR. Well, except for once. And it proved that maybe there was a reason they weren't experiment-minded.
In 1937, Illinois Central was starting to move freight trains much faster. But they were too heavy for their Pacifics and their Mikados were much too slow. They had some 2-8-4 Berkshires for 1926, but these were not the same as the famous later, faster Berkshires that NKP, C&O and Pere Marquette made famous. These engines were pretty low speed, not by intention but by fundamental design flaws. Described by an engineer : "...rode poorly above 40 mph, sometimes so roughly that the reverse gear wheel would suddenly spin into full forward gear. When that happened the throttle had to be closed at once and the valve gear returned to the proper position -- and several engineers broke an arm doing so. The trailing truck also had a tendency to derail when backing up." The derailing issue was a notorious problem with Lima's odd articulated trailing truck.
So the IC came up with a plan to build a fast freight locomotive out of them. Since the engines would not be running fully loaded, they decided to cut out one drive wheel. And because they would be running faster, they did not feel confident in the single-axle lead truck's tracking ability and ability to control oscillation (an issue on engines with odd numbers of axles as they wanted to pivot around the center axle at speed). And they wanted a 2-axle trailing truck to support a big firebox. So they built a 4-6-4 out of Berkshire #7038, retaining the Berkshire's boiler, firebox, Lima articulated trailing axle and 27" diameter cylinders but with new 73.5" drivers. The lead truck was oddly outside-framed, which was not frequently seen. Trailing trucks were equally common in outside- and inside-framed but lead trucks were typically inside-framed.
Renumbered to #1, the new freight Hudson was put into service. And was found lacking. Between incorrectly set up spring-equalization that placed too much of the engine's weight on the lead and trailing trucks, and the fact that it still had the Berkshire's big 27" cylinders, it struggled with traction. To put it in car terms, this was the equivalent of the taking a 50/50-balanced, 600hp RWD car. Then you step down from 335 rear tires to 225. And then you shave off 500lbs but only over the rear axle, to give it a 70/30 weight distribution. But you keep the 600hp. Yeah. Not ideal. In '38/'39, the spring rigging was re-equalized to put more weight on the axles and they stepped down the cylinders to 24". This made it slightly more usable, but it never really performed as IC hoped. So instead, the IC rebuilt their #7000s, leaving them as Berkshires, but making a number of improvements. The #1 was renumbered to #2499 in 1945, as shown, and then later reassigned to passenger service between Louisville, KY and Fulton, KY. In '49, they retired the US's only freight 4-6-4 and cut it up for scrap.
Interestingly, the Berkshire that donated it's boiler and other parts to the #1, also donated it's frame to another unique one-of-a-kind IC engine. This was Mikado #2199. While all the other IC Mikes used 2-10-2 frames, the #2199 instead used the #7038's frame and 63" drive wheels, witha boiler off of 1914-built Mikado #1549. The unique hybrid Mikado lasted until the end of IC steam in '55 and was considered much more successful.
Also, at least as far back as '28, Lima had proposed a similar low-drivered 4-6-4 fast freight engine in an engineering paper, proposing Unitary Machinery Support, which was their idea of moving the cylinders in as close as possible to fight oscillation, nosing, hunting and imbalance hammer blows. This idea would lose out to lightweight materials with precision balancing. Also worth noting in that paper was a proposed 2-12-6 freight engine! Sadly, no one ever called up Lima and ever ordered any 2-12-6s, although they did build the 2-6-6-6s for C&O, which could be considered similar but articulated.