Originally Posted by MotoJ
I was looking at the pics of this RPOC again. Was the sidecar tub there? I didn't notice. Anyway, on the tank- that looks like the aircleaner feature- just above the tool box lid. A snorkel, for crossing streams. That's rare, and definitely makes it a military model M-72 (the tank anyway). The front wheel stand is a military feature too, as is the sidecar frame loop that was already mentioned. Did you notice any Soviet "star" stampings on the motor anywhere?
As a matter of fact, looking at the motor close-ups again, the castings actually look pretty nice. Much nicer than my later M72. Did you notice any markings anywhere? What did the carbs say? Were they CCCP K37s, or were they German Bings? It could conceivably be a BMW R71, although that is pretty unlikely. That air cleaner and fender are really intriguing. If I lived close I'd drop by with my truck and $750 (maybe even a thou) and get a nice project to keep myself outta trouble.
Neither the front wheel stand, nor the overarn sidecar frame indicate a military model. They merely give a date range for production The overarm sidecar frame was introduced in 1942-3 to replace the stub axle (which was prone to smapping off,). IMZ made the M-72 from 1951 onwards for Government and private use. The overarm sidecar frame remained in production until 1956/7 when the M-72M and M-72N were introduced with torsion bar swingarms. Your "aircleaner" seems to be sitting on top of the fuel opening. An unlikely place for an aircleaner. The usual spot for aircleaners when tank mounted was the toolbox. Rare was a military tank aircleaner. They were also used on the M-72K (Kross) and they are just as rare.
Dating information is often found inside the electrical components.
Also no BMW R71 was ever produced with rear plunger reinforcements.