RS6 have chassis numbers starting from ......900001 to diffrence them from normal A6 derived models which shares the same 4B chassis code (they start from .....000001)
Yours would have been number 2331 of that model year. Your car was built on the 29th of January 2003.
2003 Model year production started in July 2002.
by end of July 2002 539 RS6 had been allocated chassis numbers. Not necessarily meaning built finished cars.
by end of August '02 608 RS6 total (only additional 69 allocated)
end Sept 02 = 903 in total allocated
end Oct 02 =1326 " "
end Nov 02 =1906
end Dec 02 = 2294
end Jan 03 = 2562 **
end Feb 03 = 3070
end Mar 03 = 3617
end Apr 03 = 4134
Model year production for 2003 finished at May 31st 2003. There is not final chassis number for the end of May (the final chassis number for 2003 model cars).
Best guesstimate would be somewhere around 4400.
** your car was probably allocated its chassis number in early January 2003 and was finally completed on the 29th.
Just ask at your local Audi centre for a printoff from Etka from your chassis number. It might help if you buy something to avoid the dissaproving scowls from the parts guy. (you need the parts deptartment for Etka printoffs).
This will give you all your equipment option codes.
Hope that helps