The M133 was a sort of pre production Sherpa T . In actual fact any "works" bikes were M100xxx. I'm relatively sure no Sherpas were ever given this designation. Any of the factory Sherpa riders were riding bone stock bikes that were modified to suit. If they had issues they were able to get additional parts or motors from the factory or local distributor. It'd be hard to say how many pro's bikes are still out there. If vesty, rathmell, bulto, schreiber, coultard, etc etc all got one or two bikes for the season over lets say 5 years that would be 50 sherpa t's. Of those how many are still in existence and which ones had their engines swapped out for whatever reason?. Likely a handfull. Motors and frames always matched leaving the factory. What happened after the fact is hard to say. The M199B is sort of rare. To my knowledge there was around 2000 to 2200 built. In north america it is almost nonexistent. I know of half a dozen in canada and perhaps twice that in the states. The m198B is kind of the holy grail as very few were made. My production list says 500 M27 sherpa t's were built. I know this not to be true as I have personally seen serial 801 and 865 . As I've mentioned before if your bike for example says it has serial number M15904703 then there were at least that many made.
Steve