Very interesting locomotives. They look virtually identical to the X Class locomotives (also built by SLM) on the Nilgiri Mountain Railway in India:
These engines were operating in recent years but I haven't kept up with their current status.
SLM successor DLM proposed building new replacement locomotives for the Nilgiri line which would have been updated, oil-fired versions of the originals:
(Image from their website at [
www.dlm-ag.ch]). The Nilgiri line supposedly seriously considered buying new locomotives at one point, but never could raise the financing, so they re-built their existing locomotives instead. At least one was converted to oil firing with a home-brewed system which required a small diesel generator (!!!) mounted on the rear of the locomotive to power the oil-burning apparatus.