HO 4-6-6-4 Union Pacific #3933 Model Locomotive (ATHG97972)

HO-scale Union Pacific 4-6-6-4 Challenger locomotive, road number 3933, is a detailed model designed to bring UP's WWII-era Challenger service to HO layouts. The coal-burner configuration with dual smokestacks and era-appropriate markings captures the look of 1940s–1959 operation, making it a standout centerpiece for UP-themed layouts.

Road-number-specific features for 3933 include coal burner, dual smoke stacks, and tender bunker coal extensions. The model includes illuminated number boards and headlights, a headlight that turns off in reverse, and a tender back-up light for added realism. It features pivoting front and rear engines to negotiate 18" radius curves, current pickup on all drivers, and a detailed boiler backhead with printed gauges. The sound-equipped version uses SoundTraxx Tsunami2 with two cube speakers, supports both DC and DCC operation, and offers full DCC functionality with CV adjustments (CV chart included). An upgraded loco-to-tender harness enhances durability, plus a lighted firebox with flicker behind a see-through firebox door and a brighter LED headlight. For layout compatibility, a minimum radius of 22" is recommended, and the front coupler pocket accepts an operating coupler.