I believe They should fit 64-65 post cars both Dodge and Plymouth.

 

1964 and 1965 dodge b bodies use the same doors...my 65 has 64 doors I put on

 

I also have '64 Plymouth post doors on my '65 Dodge.

 

I believe the door itself will fit on a 63 too. The window frame and vent window is different because of the change in windshield slant. The frames can be switched out. The door latch opening at the rear of the door would be slightly different than original 63 doors.

 

Door latch is a LOT different on 63. 64-5 are the same other than trim holes, Dodge and Plymouth B-body.