Overr-all configuration similar.
The RS-32 (NYC and SP only original purchasers) and RS-32 of the early 1960s and the montreal-built RS-10 and RS-18 are also members of the same "family," so a full list of spotting marks ought to take them into consideration as well.
C-420, the latests of these models, had central air system, giving it a much "cleaner" appearance: the others have numerous air-vents on the hood side that C-420 lacks. (These are a series of six (?always??sometimes?) square openings high on the sides of the long hood (with extras for units with dynamic braking?), evenly spaced on early RS-11 and bunched in two groups of three on RS32/36 (?and late RS 11?). N&W covered these with protruding louvred box-like covers on its units; they look like black square holes on others.
>>The C-420 also had much shallower notches at the top corners of its long hood (and high short hood) than the earlier models, no notches at all in low short hood.
RS32 (2000hp) and RS36 (1800 hp) were both built in the early 1960s. They are almost indistinguishable visually (the RS32 has an extra small airvent for generator cooling air in one of its hood doors), and are very similar to the RS-11. One difference: the RS-11 has, and the two models form the 1960s lack, a visible housing for air-compressor cooling on the side of the long hood, just in front of the radiator vent and about the same level as the top of the radiator opening.. This is a rectangular box, longer than it is high, projecting slightly from the side of the long hood, covered with some sort of grid or screen: in good photos from the right angle you can sometimes see loops of cooling pipe in it behind the screen.
The Canadian RS-18 is mechanically about the same as the RS-11. The slightly earlier RS-10 is mechanically more like the RS-3 (i.e. 244 engine rather tha 251) but in a carbody almost identical to that of the RS-18. The styling differs from the U.S. built RS-11/32/33 models in not having notches in the hood ends.