Some interesting equipment has shown up since Honduras, El Salvador and Guatemala have basically abandoned their rail operations all three have created railroad museums. Search youtube for "FENADESAL museo" and you will find several videos giving a tour of the backshop, roundhouse, museum and historic demonstration train. Glimpses of the 290 show up in some of the them. I don't know European designs enough to identify them.
It would seem that FEGUA took over the Guatemala side of IRCA in 1968 after they defaulted on a government loan, but IRCA continued to run the El Salvador side for a few more years. These must have been separate IRCA corporations for accounting/legal reasons but under the same common management/ownership. When FENADESAL was formed (1974?) they took over the former IRCA lines in El Salvador plus another railroad supposedly in worse condition. So where did 290 come from.
The IRCA annual reports mention that they were in talks with a German builder to try one of their diesel designs circa 1961, with financing evidently being a big part of the buying decision. The fact that IRCA wanted to try a diesel-hydraulic doesn't surprise me, there were many places in the world they were much preferred over diesel-electrics.
I was surprised in the Honduras photos to find two 70tons and a Plymouth that I think I know where they came from, plus a Brookville. I have seen a photo of a 50 ton (IRCA 705-706) lettered for El Salvador. There is no recent photo evidence of the IRCA/FENADESAL 705-706 and 802. El Salvador's civil war made the railroads a common target. But why wouldn't one of their GE's survive if the 290 managed to?
Dan