I was having a look at Peter Walnes stock and came across an black M3 he is selling. http://www.peterwalnes.com/component...mart/Itemid,1/
There is a closeup of the camera here http://www.peterwalnes.com/component...mart/Itemid,1/
The history is documented and at some stage the top was replaced during an overhaul by Leitz Canada. Everything says it is an M3 not an M2 but it clearly says M2 on the top.
Even the receipt shows M2 overwritten by M3!
Bearing in mind the film counter, I wouldn't have thought the 2 tops were interchangeable. Can anyone shed any light on this anomaly?