Used in conjunction with the front bracket, bolts onto stud protruding from the rear of your radio, rather hard to find once the original radio has been removed. One exception; 1972-73 Mercury Cougar and Ford Mustang AM/FM radios used a different bracket marked D2ZA-18888-AB.
"These guys have got to be the most professional I've dealt with in the 4 years I've been restoring my Mustang and Cougar. I have had nothing but pleasant conversations even though I tend to be long winded. Dan D. (mercurycougar.net)