a-body rear end help

im thinking on changing rear end on my 68 valiant , i want to put a 8 3/4 in it , what cars rear end will work ? will rear end have to come out of a a-body ? or will a b-body work ? and will i need to change the springs ? its been over 20 years since i own a decent mopar and im thinking about upgrading brakes and rearend. all help will be greatfull



















/