It's Dutch built, I think the firm later became Dynaf Spruyt or Spruyt energie NV and they folded in 2007. I really don't know anything about this generator but the lights/warnings panel is quite comprehensive and the 115V/400Hz fits. My concern would be that I cannot see any cables and it's not really of much use without those. It certainly would be more useful if on wheels, but it may have been modified for another purpose at some point, removing the wheels, as it was most likely repainted as well. I would guess at the interior green being the original colour, which points to a military purpose originally. Finding the specs will be difficult.