I'm also looking around a bit - for a CUCV maybe - my 2 ct on what I found so far:
First of all, try to find your dream MV locally to avoid the red tape and costs for a direct import. There are sites, that describe the process - but be warned: It's expensive (if I'm right about 20% customs, 19% sales tax on the vehicle price plus the customs fee, transport, localization, TUeV etc)... Import is one thing, export the other - not sure, whether you even can export a MV out of the US of A: I saw a number of US based offers explicitly saying, that they are not allowed to sell outside the US by law.
Adresses I'm aware of:
Morlock Motors, already mentioned above, but want to add some notes: Long time in business w/MV, but honestly wouldn't be my first choice. Saw some side notes about their quality and working style, e.g. how they make the required changes to get the German registration. May search for "steel buddies dmax.de", you'll find some videos and get the picture.
Try
http://www.horsepowerparts.de/ - I found them recently @mobile.de, their offers look quite promising, haven't tested them, though.
May also try ebay and similar platforms - there are some sellers offering army surplus and parts.
Finally: Make sure your MV is older than 30yrs and in good shape to qualify for a historic registration - saves you a fortune on taxes and insurance, plus you can forget about those f...g Umweltzones
A good dealer will provide the paperwork for this.
Hope it's useful...
