new to a body .k member /drive line info

hello.been out of mopars for a while and sure things have changed .need info on swapping a small blkock into a 66 valiant .what years fir the 66 .also rear end swap will 70s duster fit .also disc brake swap do you change a arm ,or just spindles and what works .also someone told me the early mustang fits in the rear end to get the 4-5 bolt pattern .i dont want to put brand x into the valiant .but parts are hard to find here in indiana .i know thes questions have probably been asked many times .if you can tell me the blog ill go to it.still reseaching the site may find it ?thanks :burnout: