I found a gearbox from a Seicento Abarth, at least that`s what the seller says. How can I identify its really an 4.07 FD Abarth box? He said the only code on the box is 0.5.10.15 which is odd...
Here is a picture with the box, maybe someone can help me to identify it:

Some (but probably not all) Sei Abarths were factory built and should have a different VIN number.

But otherwise you'll probably have to turn the box and count the revs at the cups.