The Lionel Canadian Pacific F-3 No. 2373 is the rarest of the F-3s. It was only available for one year: 1957. This engine was produced on a GRAY body that is painted MAROON with YELLOW stripes and heat-stamped lettering. Reproduction shells have silk-screened application of these colors. A railroad herald decal decorates the front of the A Unit. The chassis is BLACK, as are the truck side frames and the front pilot skirts.

This version has louvered roof vents, filled in portholes, cast in side ladders, magnetic disc couplers on the front ends, and solid rear couplers. This diesel was equipped with a horn that was operated by a D Cell battery, and a three position directional unit whose control lever was adjustable from underneath the chassis. The dual vertical worm drive motors powered each axle that utilized Magnetraction. There was no B Unit created for this road name during the post-war period. There are two variations:

Variation A: Normal height raised cab ladders.

Variation B: Higher raised cab ladders. This variantion is usually found on body molds that are ORANGE in color.

All of the Lionel F-3s are designed to work on the larger radius of O Gauge track. When used with O27 Gauge track this diesel will scrape the switch machine housing on the early versions of the No. 1122 O27 Switches when passing through the curved turnout. Evidence of scrapes on the fuel tank of these diesels is a sure indication of operation on O27 track.