The horn relay in my 72 Nova has honked it's last horn. The relay is no longer available from GM or the aftermarket from what i've found. My local GM dealer said all 72 chevys used the same horn relay. I picked up a new one for an impala from hubbards impala parts, but it does not look anything like the original and has a third terminal on it. i went to the AC Delco sight and the part # I have only goes up to 1971 per their info online. Can anyone tell me if this relay will work or what others might cross over. The Delco part # is D1756. or GM #12339248. Thanks.