I'm not the type of guy who knows that stuff off by heart, loads of useful info on the net though mate, and more than a few guys around here know there stuff when it comes to M-Codes etc...
...If you only have the chassis number i'd suggest you get a 'birth certificate' for ya bus, i got mine through this week, and am currently trying to figure out why the hell my bus spent the first three months of its life in ICELAND ... Must be the only RHD Icelandic import in the UK!