I'm not sure which Leica M3D (there was more than one) was sold at auction, but Duncan mentions them in his afterword to "I Protest!" as being the main camera he shot his Vietnam photos on. So they were working cameras, once, unlike the other two. That's two different parts of the Leica mystique: Leitz was still close enough to the hand craft tradition that they turned out custom builds (not just serial numbers), and that those custom cameras were used to make iconic photos. If I had a fortune to spend on a trophy camera, I'd spend it on that one.