RS2 - Santa Fe had only one, 2099 . It was originally built as a demonstrator unit by Alco, the body was closer to an RS2, but the insides were an RS3, built in 1950, it was acquired from TP&W in October 1950, Santa Fe renumbered it to 2110 and painted in black/silver zebra stripe.
Santa Fe later renumbered it to 2099 in May 1952. It was later repainted to blue/yellow. Retired in 1969. Class was 2099. Most RS3s were factory equipped with Wabco A2 (long bell) sounding D above middle C. There might have been a few Wabco A6 applications.
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A nice b&w close in view of the 2099 appears on page 212 in John B. McCall's book: EARLY DIESEL DAZE. The zebra striped unit indeed has a Leslie A200-156 single tone horn and is located on the centerline of the cab roof facing short hood end in the undated photo. Of interest, the unit had a steam boiler and dual controls, and spent most of it's service career in passenger switching, branch line, and local passenger service.
When Santa Fe first got it, the long hood was designated the front, hence the stripes coming to a peak on the long hood and a V on the short hood (the "rear"). Some time later, the short hood was designated the front and the striping pattern was reversed to put the peak on the short hood. A photo of the unit in this later configuration is in Iron Horses of the Santa Fe Trail.
There are 2 phases of RS2 production, early and late, Feb 50 to may 50 the horsepower was increased to 1600. Santa Fe had no RS3's therefore.
There is a number 2098 is in Campo, Ca, which is former Kennecott Copper Corp. RS-2 #103 painted up to resemble a Santa Fe unit.
Closest G scale model: RS3 by Aristo, Art-22203, zebra stripe, road numbers 2094 and 2099.
RS2-3, difference 3 has battery box on running board behind cab, rs2 fuel fill cap and gauge on side of cab (rs3 under frame), RS2 did not have battery boxes outside short cab.