It is a nice looking camper. It seems like it'd be an ideal candidate for an engine swap. Maybe a 3.9 liter Cummins B-series 4-cylinder diesel or one of Isuzu's excellent small diesels. Or, if fuel economy is less of a concern, a small block Ford or Chevy.

Even an OM617 would be an improvement, but the thing would still be a total dog.

Aaron