A-Body 8 3/4 rear end complete drum to drum- 3.55 posi

what would you have to have for the rear and the k member [what engine is this for ??].I have a big block 1967 dart that has had the 6 cyl k member butchered and would like to put in a small block k member and the adapter motor mounts [the mount rubber has been removed on the drivers side as it sits now and is rough as a cob driving it],so just need to know what you need for everything ,thanks for your time on this