Re: horn relay
1972 Chevelles' have a unique horn relay. There are 2 spade style connections for "in" from the interior horn button(s) and "out" to the horn(s). They no longer contained an warning buzzer for the "key minder". They have a threaded stud to provide a junction for the power distribution as well as providing the (+) connection to the horn relay itself.
For a picture, scroll down to the bottom of this page:
-If you don't stand for something, you'll fall for anything.