Sorry for coming back to an already solved puzzle, but I've a question?
Why do you call it "Siata-Abarth"? I know the 170S as the last Siata model before its first financial crack. The short Siata-Abarth adventure began one year later with an offer of only 4 Fiat 600-based model, as far as i know. No Abarth parts should be in the 170S.
Thanks,
Alessandro.