The Lionel Union Pacific No. 645 Switcher was produced in 1969 on an unpainted YELLOW body with heat-stamped RED striping and lettering on the left side, "SERVES ALL THE WEST" and on the right side, "ROAD OF The Streamliners." Unlike its predecessor, No. 635 issued uncataloged four years earlier, this version was not numbered, nor did not have the "NEW 7-58" and "U. P." imprints on the front. Equipped with a two position directional unit whose control lever was adjustable from the top of the body, there is no ornamental horn or bell on this body that is mounted on a sheet metal frame. Equipped with solid non-operating couplers at both ends. This switcher came with a Type IVB motor that used a traction tire on one wheel. It was lighted at the front end and came with a headlight lens. There are no variations.

All of the Lionel NW-2 switchers are designed to work on the tighter radius of O27 gauge track, but they will run equally well on O gauge track.