Hey RAII4-speed, You are correct on the 73s. I own a 73 Dart Sport 340 and it came standard with power disc brakes and is also listed in the literature for the 73 that power disc brakes were standard on the 340 car.The 72s have me perplexed as I owned a 72 Demon 340 and it was a manual drum brake car. I have also looked at other 72s that had manual drum brakes and were legit 340 cars.On ebay right now there is a HB1 Blue 72 Demon 340 a factory 340 3 speed stick car and it has manual drum brakes on it. Dont know if maybe it depends on when they were built? I also parted a 72 340 Duster that was rusted completely out and it to had manual drum brakes on it.