Rear end woes. 1965 Chevy C10 pickup.?

99-03 (I think 03, whenever till the body style changed again) model trucks had factory rear disc brakes. Amount of work to install depends on your rear suspension type (leaf vs trailing arm & coil) or for all I know you have a trick 4-link. But about the extent of work would be welding new spring perches on the axle tube and I would ume a conversion u-joint.