Several ways to go.
I have new (modified) firma 5 smoke units and also used ones removed from converted locos. Contact me off list for details.
Details on replacing a Seuthe unit
http://www.tuveson.com/Mikado/...acing_smoke_unit.htm
Details on modifying a Firma 5 Seuthe unit to fit.
http://www.tuveson.com/convert...modifying_seuthe.htm
And converting to a Fan smoke unit.
http://www.tuveson.com/nyc-mikado/nyc-mikado.html
Carl T.