Just about all of the Gwagons before model year 2002 were imported by a company called Europa.
http://www.gwagon.com/flash.html
They know these trucks even better than MBUSA. Any parts you would need for it will most likely be sourced by them or an aftermarket supplier if it's a grey market specific part.
Euro G's have a spare key issue which has become a problem if they are equipped with the infra-red system.
If you do indeed buy this truck make sure it has more than one key as it is almost impossible to get a gray market Gwagon key lately. Even Europa can't get them anymore.
IMO G's are the coolest MB's ever built. Tough as nails too