Union Pacific FEF-4 Class 4-8-4

The Union Pacific FEF-4 was a proposed addition to the Union Pacific's long line of successful 4-8-4s. 
==== Ideas for the design ====
Sometime around 1945, the Union Pacific, under the direction of Fetters and Otto Jableman, were toying around with the possibility of a fourth group of 4-8-4s. The engine, dubbed "the FEF-4", was to take the already successful FEF-3 class and improve upon it with more modern appliances. The locomotive would've featured Poppet valve gear, a twin sealed beam headlight, an oscillating Mars light, a different smoke deflector design with the deflectors pushed in closer to the smokebox barrel, and an all-weather cab. There was also contemplation about changing the design of the tender; either they would stick with the same 4-10-0 centipede tender which they had been using with the Challengers, Big Boys, and FEF-3s, or design an all new 4 or 6 axle tender to go behind the engine.
The engines would've been oil fired from the very start, as opposed to the FEF-3s which were coal fired when first built and then later converted to burn oil.
==== Why wasn't it built? ====
By the late 1940s, with the War winding down and restrictions being lifted on diesel locomotive manufacturers, management was more interested in buying more diesel locomotives rather than building more steam locomotives. Thus, the FEF-3s ended up being the last steam locomotives ordered by the UP, and 844 itself was the last steam locomotive built for the UP.
It should be worth noting that at about this time, the Union Pacific was also considering ordering a third batch of Big Boys, which would've been assigned to the Los Angeles and Salt Lake Divisions, but once again, with the war ending and the restrictions on diesel locomotive manufacturers being lifted, management was more interested in dieselizing the UP than in buying more Big Boys.