Disc brakes were not standard, I have a 74 318 car with big drums up front.....
- Disc brakes standard with 318 V8
I believe it was a delete option ( credit ) . I've seen exactly one '73 Duster , 318-powered ( E44 on tag ; "G" in v.i.n. ) , which had manual drum brakes , and was coded as such on its fender tag ; I believe the sales code is "B12" or "B13" .
Can't blame anyone whom wanted for drums back in '73 . Those trouble-prone Kelsey-Hayes 4 piston brakes were a plague , and were used through at least 1972 on "A" Bodies ; not sure if most were aware that those junks were dropped by '73 / '74 .
Same thing goes for 1970 & up "B" bodies : 1969 was the last year that Road Runners , et al. , used those K-H 4 piston brakes ; yet quite a few "B" bodies still had those dumb drums instead of discs ( I've seen "Super Track Pak" optioned cars that had the discs deleted . Perhaps that was more of a race track deal , as drums were more desirable for 1/4 milers than disc brakes , as they tend to "drag" ) .