Santa Fe F3 number boards

Santa Fe numbered its cab and booster units differently than any other railroad.  Engine 36 was a four-unit (A-B-B-A) rednose passenger F3, built early in 1949.

The first cab unit had the suffix "L", so, in your example, it was numbered unit 36L.  The number board displayed only the number 36.  The small number painted in the stripe at the rear corners of the locomotive was 36.  The letter L did not appear anywhere on the outside of the locomotive.  (I probably should not mention that there were a few much later instances of an L being painted above the anti climber, as these were deviations from standard practice.)

The second and third units (both cabless boosters) were numbered 36A and 36B.  The small numbers painted in the stripe at the rear corner of the units were, respectively, 36A and 36B.

The trailing cab unit was numbered 36C.  Originally, it only displayed the number 36 in the number box, but had a small letter C painted in the bottom of the nose herald vertical stripe, just above the anti-climber.  The small number painted in the stripe at the rear corners of the locomotive was 36C.

In addition to numbering its passenger units differently, Santa Fe managed its passenger locomotive fleet more tightly than other railroads.  The four-unit passenger diesels stayed together in numeric consists, and were usually turned at the final terminal of their train, in order to equalize wheel wear from curves.  Thus, in the days through the late 1950's, the L unit actually was usually the leading unit.  Sometimes, though, there was no time to wye the engine and it was sent back out with the C unit leading.  The practice of religiously turning the locomotive consist ended in the late 1950's, and it was not uncommon thereafter to see the four unit consist led by the C unit.  In the early 1960's, the railroad discontinued leaving numeric consists together.

About 1955, the railroad changed all the number boards on C units, to include the letter C.  Thereafter, the locomotive 36C in your example displayed 36C in the number boards, retaining the small C on the lower nose stripe and 36C at the rear.

The "blue cards" (ICC inspection cards, later, FRA inspection cards) posted in holders mounted inside the cabs of the A units and on the engine control panels of the B units, displayed, respectively, 36L, 36A, 36B, and 36C.

Santa Fe never used dashes between the road number and the letter suffix.

A-B-B-A blue FT, F3, F7, and F9 units were treated the same way, but also had a number panel with glass reflectors mounted on the nose, which showed the same number as the number boards.

Thanks Tom for the education on Santa Fe protocol. Sincerely Brian

Brian, just to elaborate a little, the reason that both cab units of a Santa Fe locomotive could display the same number is that they were never run on different trains, always staying together in the same consist.  When trains were run by timetable and train orders -- instead of by CTC or by Track Warrant Control -- the number displayed on the locomotive was absolutely critical to identifying superior trains.  The Santa Fe split a 4-unit A-B-B-A freight F7 consist into two A-B consists to power two local wheat haulers during the Kansas wheat rush, and they both had the same number displayed. Fortunately, there was no train wreck because of it, but the railroad saw clearly that they needed to add the letter C to the number boards of all C units.  That's why there was a change.