The Lionel Milwaukee Road F-3 No. 2378 was only available in 1956. Produced on a GRAY shell, a heat-stamp was used to apply the lettering and and lines. A decal is on the front of the A Unit. Reproduction shells have silk-screened application of these colors. The chassis is BLACK, as are the truck side frames and the front pilot skirt.

This version has louvered roof vents, filled in portholes, cast in side ladders, magnetic disc coupler on the front end of the A Unit, and all other couplers are solid non-operating. 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.

After the inital run of these diesels Lionel would stop producing them with the upper YELLOW stripe. This was either because it was poorly applied, or it was just another cost-cutting measure.

There are three variations:

Variation A: has the upper YELLOW stripe.

Variation B: without the upper YELLOW stripe.

Variation C: had a combination of this stripe on the A and B units.

All of the Lionel F-3’s 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 version 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.