HO F3A / F3B Locomotive Set Southern Pacific #307, #505 (ATHG19578)

HO F3A/F3B Locomotive Set — Southern Pacific #307 and #505. This two-unit HO-scale pairing recreates SP’s classic F3 diesel locomotives, delivering an authentic late-1940s freight power pair for Southern Pacific lashups on a model railroad layout.

Bringing the prototype to life, these F3 Phase II locomotives feature slot-style dynamic brakes, dual single-note horns on the A units, a freight pilot, and as-delivered grab irons and skirts. The models ride on a heavy die-cast frame with a Genesis drive, a 5-pole skew-wound motor, and all-wheel traction, with RP25 wheels for smooth operation on most HO track. Detail is extensive: see-through cab windows with full interiors, etched metal fan grilles, lift rings, wire grab irons, sanding lines, and separately applied metal parts, plus trainline and MU hoses and lit signals where applicable. Body-mounted scale knuckle couplers (Kadee-compatible) and Quick Plug 21-pin NEM DCC compatibility simplify setup, while LED headlights and directional lighting maintain a realistic appearance. The design supports operation on HO curves, with a minimum radius of 18 inches (22 inches recommended). Sound-equipped variants add an onboard DCC decoder with SoundTraxx Tsunami2, dual cube speakers, operation in both DC and DCC, separate sound boards for each unit, a CV chart for tuning, and prototypical lighting effects such as beacons or Gyralight as appropriate, plus bell and engine sounds that can be controlled under DCC.