MTH adds RailKing Big Boy steam locomotive in six paint schemes

Six paint schemes and Proto-Sound 3.0 are the whole argument here. MTH Electric Trains put a new RailKing 4-8-8-4 Big Boy steam locomotive on the table at $929.95, with delivery expected in September 2026, and the spec sheet makes clear who it is for: operators who want the drama of Union Pacific’s giant articulated engine without needing a layout built for the prototype’s footprint.

The RailKing release adds operating LED lights and O-31 operation, which matters as much as the paint variety. O-31 keeps the model in reach of tighter layouts, while the six schemes give the same engine a broader shelf presence than a single road number ever could. For buyers who already own a Big Boy, that variety is the main pitch. For collectors, it is the kind of lineup that can turn one locomotive into a comparison piece, especially when the Big Boy silhouette is doing so much of the visual work.

MTH has leaned on the Big Boy before. A RailKing Union Pacific Imperial Big Boy with Proto-Sound 3.0 was listed at $799.95 and delivered in February 2019, with two motors and four traction tires. That earlier version was built for hard pulling and gave buyers a more traditional RailKing value proposition. The new 2026 locomotive asks more money, but the added visual package and the multi-scheme approach make the newer release feel aimed less at pure pulling power and more at presentation, sound and layout flexibility.

The company has also gone upscale with the same prototype. Its O Scale Premier Big Boy from 2015 carried a $1,599.95 list price, and the 2026 Premier Big Boy is listed at $1,899.95 with December 2026 delivery. That Premier model includes a quillable, variable-intensity steaming whistle controllable from a DCS handheld controller, smartphone or tablet, which pushes the feature set well beyond the RailKing version. The difference between the two lines is plain: RailKing is the more accessible big-steam buy, while Premier is the showcase piece with deeper control options.

The prototype still does most of the selling. MTH describes the Big Boy as designed to pull a 3,600-ton train unassisted over the Wasatch Mountains in Utah, and calls it a major symbol of American railroading and the American West. That legend is why each new release lands with such force. The new RailKing version does not reinvent the Big Boy, but with six paint schemes, Proto-Sound 3.0 and O-31 compatibility, it gives buyers a fresh answer to the same old question: one more Big Boy, or one too many.