The Lionel Santa Fe No. 634 Switcher was issued in 1963 and again in 1965 and 1966. This painted BLUE engine initially came with YELLOW heat-stamped lettering and safety stripes on the front and rear, but later issues would not have the safety stripes. Although the holes for the bell, horn and radio antenna have been filled, this diesel is most commonly found with the holes for the front marker lights.

It was equipped with a two position directional unit whose control lever was adjustable from the top of the body that was mounted on the late version of the sheet metal frame. This engine was powered by one Type IVA motor, and had a solid plastic coupler on the front, and a die-cast metal solid coupler on the rear.

Due to the lack of magnetraction, Lionel had a problem with this unit gaining enough traction to pull a string of cars. Even though the motor had a "traction tire," this was not enough, and the 1965 and 1966 productions have a metal weight secured to the underside of the body. This required a modification to the body to accept the screws that held this weight in place.

There are three variations:

Variation A: Has the safety stripes on the hood and the back of the cab, but no holes for the marker lenses in front. 1963 production.

Variation B: Has the safety stripes, but has holes for the marker lenses in front. 1963 production.

Variation C: Without the safety stripes and, but has holes for the marker lenses in front. 1965 & 1966 production.

Lionel issued this diesel for use on O27 Gauge track, but it will also operate on the larger radius curves of O Gauge track.