63/66 Valiants

A simple question but there's a lot of details to cover four model years.
In general most if the chassis & mechanical parts such as suspension, brakes, power train etc are similar but there are yearly upgrades ( like the '63 firewall needs to be modified to fit a V8 & ' 66 doesn't 't have a ball & trunion on the driveshaft). The pedals for all four year should be the same.
The body structure is also very similar with the underbody very similar year to year but the body panels have model year changes. The front windshield is the same '63 to '66, even the convertible but not the rear glass ('66 is a one year only).
I think '63 & '66 have a lot of one year only body & trim parts.
Things like carpet & vinyl door panels interchange but of course their appearance changes year to year and are even different between trim levels (100 vs 200 vs Signet ) in the same model year.
And of course there are many common parts between the Barracuda & Dodge Dart models.

Hope this helps.