Originally Posted by brokenrobot
I think what you've got (if it's the same as my 310, picked up a week ago) is 105; mine has the model number 105 engraved on the rear of the derailleurs and brakes with a squiggley arrow thing on the front, and the word "Signature" only on the crank (which may or may not be Shimano - I haven't looked closely). Does yours actually say "signature" on every component? Model/part numbers from the backs may be helpful...
-chris
The 105 arabesque parts that I have, have just 'Shimano' and a 'flowery' arrow engraved on the front of the derailleurs and the crank arms; the engravings seem to be filled in with gold or yellow paint. I found out they were 105 only by the model/part numbers.