>>9440516The Narrow gauge scales I'm aware of are On3, which is pretty limited, On30 (HO gauge) which is heavily supported by Bachmann, On18 (N gauge) which is mostly cottage industry kitbash and HOn3 (N gauge) which has a fair amount of support. I know in O scale, On30 stands in for both 2 foot and three foot narrow gauge prototypes. Peco sells On30 track with the long, widely spaced ties typically found on 2 foot gauge railroads and Bachmann makes a number of two foot gauge type locos like this H K Porter 0-4-0st. front to back, all O scale; On18, On30, O gauge.
