Looks similar to mine. That 51 on the BB is the frame size. Mine says 57, as its a 57cm frame.



And info on mine(maybe itll help you out)

The frame is probably an Olmo Corsica from 1989
The 'faded' sticker on the downtube would be a 50th anniversary sticker, and since Olmo began in 1939, that dates it as 1989 as above.
The tubing is hi-tensile as on the pic (equivalent to columbus aelle or whatever it is called), which later that year (I believe) was changed to TT 8.0, which is the decal found on most other corsica's
Corsica's came specced with mostly shim 600

Yours is prob slightly lower end with the 105 groupset. Good luck on finding out more.