Right I finally decided to spend a few quid on the wifes unloved Stumpjumper, new SLX chain and cassette from Merlin and a new middle ring from the classifieds on here.

The 32t middle ring doesn't fit! only difference is the one on there has M9 n32 stamped on it and the new one has M9 S32 on it. All fine but been on CRC and Merlin and can find no reference to the numbers, which one do I need!/ what have I got from the classifieds!? Was told it was deore so should fit?

The cranket is a shimano/spesh hollowtech jobbie on isis drive from about 2006/7.