This is the HO Scale Stewart FT Unit Oper. Diesel Diaphragm (Gray) from American Limited Models.
Make your classic A and B passenger (or freight) units look as good as the cars they pull with prototypical close-coupling and detailed diaphragms between units. Parts are molded in gray or black to match prototype practice.
Make your earliest F units look their best with these parts. Uses the loco's scale (short) drawbar and includes three complete diamphragm assemblies, enough for one A unit and one B unit.