why cant we use B or E front disc?

i have a 70 dart with 10" manual drums. i want to change to manual disc and want to know exactly what fits. i"ve read so much stuff on here im cross eyed. lol. thanks

tom

I'm using FMJ front brakes on my 63 Dart. All you need are the FMJ brake assemblies, large ball joint upper control arms from 73-76 disc brake A bodies and the lower ball joint for the same application. Instant bolt on.