70 duster 8 3/4 conversion to 4.5 drum or disk hardware
if you want oem rear large pattern brakes you will need new axles that have the correct offset mentioned above
for these probably easiest to buy new...~$350 ish see dr diff you can't go wrong
backing plates from any car or truck with 7.25, 8.25, 8.75, 9.25 rear and the 5x4.5 bolt pattern....say $75 for a core set
new drums...check for your donor application budget $50 each
new wheel cylinders $5 each
new hardware and spring kit...$10 ?
new brake shoes..check your application but budget $30
might want to replace axle seals while you have it apart
your also going to need new rims and potentially tires so bake that into the equation.
or find a lbp b body rear complete... 100 typical price with open diff...and relocate the spring perches.