63/66 Valiants

This is mostly from memory.
Starting at the front it's 66 only for Valiant& Barracuda bumpers , fenders and hoods. The grills for Valiant & Barracudaca are different but do interchange and the head light bezels are slightly different & might also interchange. The windshield is the same for all ' 64, '65 & '66 Valiant, Barracuda and Darts ( maybe even '63).
The doors for hard tops, including the glass, also fit '64-' 66 Valiant, Barracuda & Dart but the hole I the sheet metal is slightly different for '66 but it can be made to work, of course the sedan versions have the window frame & convertibles have a different vent window frame. Door handles, arm rests, window cranks are all the same for '64-'66, the interior vinyl door panels will interchange but will have different patterns.
The '66 buckets sets are common with '67 model year A-bodies, '64-'65 seats will fit but may interfere if you have a center console. For rear seats the convertible is narrower than the others but I think '64-'66 are interchangeable. I'm not familiar enough with the station wagons.
The Valiant got a new roof & rear window in'66 which are common for two & four door models, these are one year only parts & there is no reproduction rear glass or window seals available. Not sure about rear side glass but I'm sure convertible glass is unique.
I think trunk lid was carry over in '66 but the quarter panels and rear bumper are new for '66 & common between Valiant & Barracuda.
A lot of small items are common on all '64-'66 Valiant, Dart & Barracuda models such as sun visors (except convertibles) & mirrors.
Hope this helps.
Exterior trim is usually different year to year and even different between the 1966 Valiant 100, Valiant 200 & Signet models.
Hope this helps.