Cannondale R400 Frame Number Decoding

[repairtec]

I'm trying to identify this Cannondale R400 frame ID number stamped on the BB its the same bike I've posted under photo's elsewhere:

8792100C7780
3RRD3E 56

its stamped as shown above but the RRD and E in line 2 may be wrong as the stamping is poor, the 56 is the frame size. Note the Cannondale and Bikepedia webbies don't seem to recognise them but I would like to trace the real spec and year of manufacture of this frame.

Thanks in advance