why cant we use B or E front disc?
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.
Yep, you can use any of the FMJ stuff too, including the spindles. They have slightly different geometry than the '73 up A body spindles, but not enough for most people to even notice. And the change in geometry actually improves the camber gain while cornering, so you can argue they're actually better than a body spindles. This is pretty nice, because a lot of wrecking yards still have FMJ clunkers in their yards, you can pull the spindles and brakes off of some of those models all the way up to '89.
You can also use the larger 11.75" FMJ rotors if you get the caliper brackets to go along with them, they use the same spindles, control arms, and even calipers as the regular '73 up 10.97" rotors do for an A-body. You do need to have 15" rims though, as 14" rims will hit the calipers.
Here's a list of all the Mopars that use the same 10.98" rotor. You can also pull spindles and calipers off of any of these cars. Some will have pin type calipers, but if you grab everything from the spindle out you'll get the right caliper brackets. Some of them also had the 11.75" rotors from '76 to '81.
CHRYSLER CORDOBA (1975 - 1983)
CHRYSLER FIFTH AVENUE (1983 - 1989)
CHRYSLER IMPERIAL (1981 - 1983)
CHRYSLER LEBARON (1977 - 1981)
CHRYSLER NEW YORKER 1982
CHRYSLER TOWN & COUNTRY (1978 - 1981)
DODGE ASPEN (1976 - 1980)
DODGE CHALLENGER (1973 - 1974)
DODGE CHARGER (1973 - 1976)
DODGE CORONET (1973 - 1975)
DODGE DART (1973 - 1976)
DODGE DIPLOMAT (1977 - 1989)
DODGE MIRADA (1980 - 1983)
PLYMOUTH BARRACUDA (1973 - 1974)
PLYMOUTH CARAVELLE (1978 - 1985)
PLYMOUTH CUDA (1973 - 1974)
PLYMOUTH DUSTER (1973 - 1976)
PLYMOUTH FURY 1975
PLYMOUTH GRAN FURY (1982 - 1989)
PLYMOUTH SATELLITE (1973 - 1974)
PLYMOUTH SCAMP (1973 - 1976)
PLYMOUTH VALIANT (1973 - 1976)
PLYMOUTH VOLARE (1976 - 1980)