rear disc brakes

1969.5 maverick 9'' rear stock mav 8'' rear axles ......97 merc - mountineer all i had to do is open up the holes on the bracket where the axle bolts up to i didnt do any other mods to the brakes..stock master and valve ..4 piston disc brakes up front .... it stops better i was stomping on the brakes and only locked up the rears one time