Perhaps you were thinking of the 20 ton gasoline SFNW locomotive that operated only in Bernalillo (The Well) in the 1960s.
It is superficially similar to #50 but was standard gauge and lacked sidebars and the custom coupler shifter. It was later converted to diesel.
M I K A D O 282 ⊙⊙⊙⊙⊙⊙ ⊙⊙ ⊙⊙ (talk) (Help Wanted!) 18:38, 5 August 2020 (UTC)
