The Krupp Protze is what I think you mean, which was built from 1934. I'm not sure if there was ever a civilian version made, but it was heavy on gas in any case, so might not be the best thing for an expedition. The Laffly S15 was a similar design, but again I'm not aware of any civilian models.
People were innovative and keen to build and convert, so with some tools and a light workshop, they could produce pretty much anything on a chassis, suitable for their uses, look at the home-made armoured cars of the Spanish Civil War (not counting the factory produced ones).