63/66 Valiants

search this site-- most of your questions have been answered, there is no cliff's notes version as to what fits on your car-- the posts above have been as complete as can be with such a broad topic.

rear ends from 1960 to 1976 abody cars will all physically fit under your car with a direct bolt in--- there are numerous differences-- general 7 1/4,(all years some 73-76 are lbp ) 8 3/4 (performance/heavy duty 65-72 sbp) & 8 1/4 (73-76) stronger than the 7 1/4 with the lbp style bolt pattern .
steering column in 66 has different wiring than previous years-- match manual & manual or power & power & they are the same size.
Glass-- hardtop to hardtop, convertible to convertible & sedan to sedan will get you the correct fit (probably are exceptions)
You need to go to the throne room & search your ride & what parts you might need some one has worked on a 66 before & might have your specific answer.
another note your car is the 1st year of the slip yoke drive shaft-- a lot of parts a 1966 only. Lawrence