The Lionel Baltimore & Ohio Budd Unit No. 404 was available in 1957 and 1958. This motorized baggage/mail diesel would be painted SILVER with BLUE heat-stamped lettering and "BUDD RDC-4" adhesive plates. Equipped with a horn that used a "D" Size battery, there were also ornamental horns at each end. The EMD F-3 Trucks came with operating magnetic couplers. Lighted by three lamps that showed off the silhouetted window strips and lighted both headlights, this engine came with two axle Magnetraction, and a three position directional unit that controlled a single vertical worm drive motor. There are no variations.

Note the "X" suffix on the lower picture of the box end above. The "X" indicates that this Budd Unit was issued in a set.

All of the Lionel Budd units are designed to work on the tighter radius of O27 Gauge track, but they will run equally well on O Gauge track.