Look on the cast side of the horns for a 3-digit number...that will help ID the horns. It will also be marked 12V. All of the GM cars used the Delco-Remy sea shell horns, so that set could have come off of one of the big cars from the late 50's.
I believe 1957 was the first year for the stamped steel cover like your right horn has...the earlier horns had a round (half of a sphere) cover.
The HI note horn was an accessory on the TF trucks and was mounted on the passenger side of the radiator core support...it's a mirror image of the LOW horn
Mike B
