HI Peter,
I checked them out this afternoon, and they are BR M734's. I assume this was the XT number for the cantilever brakes as my crankset is XT, and is FC M730.
I wondered what the small black rings were for - I saw one when I got them out this afternoon to take a photo - I will have to check the box to see if there are any more in there. There were some washers, but I assume you can just get those from a hardware store, or motor parts place? Other than that as per the picture.
Cheers
Ian