With the internet, finding a needle in a haystack is no longer an issue. 

I just put the following item up on a Craigslist site.   Let's see what happens!

VolksWagen VW 6 volt Eberspacher gas heater which appears to be complete. The model number of the unit appears to be K5. (see nomenclature plate in image above). I have had this unit in my garage for about 30 years - the metal is completely sound. Has heat output of 3200 k/cal per hour which I believe is for a Van not a bug. I did not take the unit out of the original vehicle. Because the nomenclature plate reads "Germany" and not "West Germany" this unit could be from the 1930s or 40s - pre WWII. The device (Gerat) number is 8478. http://www.type2.com/library/heating/b2ht.htm is a web site which describes the installation of another model of gas vw heater. I got the link from this site http://messa.us/VW_Bus/gas_heater.html.

On Ebay similar heaters run anywhere from $100 to $600. I am starting at $400 for this unit. If my price is out of whack, please email me (click on name at top of this article)  with comparable sales and I will get in line.  The last image is just a joke! Image is from Google image page here https://www.google.com/search?q=vw+van+gas+heater&hl=en&client=firefox-a&hs=IHp&rls=org.mozilla:en-US:official&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=PJMhT4PMDY660QGF_NDzCA&ved=0CKIBELAE&biw=1252&bih=610