Hello John,
That’s a pretty picture!
There was no sign of any of the Oahu locos when I was at Sonsonate in April 2012. The only steam locos at the roundhouse/depot site were IRCA 2-8-0s nos 110 and 117 - plus El Salvador Railway 4-6-0 no 8 which was on display in the outskirts of the town. One of the works plates of an Oahu engine is incorporated in a memorial to the railwaymen at the entrance to the workshops area at San Salvador and I think it is the only surviving part of any of them now.
Best wishes,
James