This Bendix dual diaphragm power booster was generally used on disc brake cars. The Hemi booster had 3/8" mounting studs to the bracket. 440 boosters only had 5/16" studs, and the stud pattern was different than the Hemi piece. The Hemi style booster bracket was used in 440 cars only in 1967. For 1968 and up, the booster was bolted directly to the firewall. My 1967 440 R/T was originally a non-power drum brake car. I sourced a 4-piston disc brake setup and booster off a 1969 Charger and installed it on my car. I mounted the booster on the firewall, without a bracket, as it was on the Charger. Every thing has worked fine for over 30 years, and no one has called me out for not having the proper booster bracket.