63 dodge dart drive door rattles

My convertible driver door rattles and when closed fully, from the outside I can push the door in and out at least a half inch or more.
The passenger door closes fully but does not allow me to push it like the drivers side. I realize that the drivers door has been opened way more than the passengers so is worn to a much greater degree.
Question is will a new door gasket seal fix this or is there more adjustment involved. I also see there is a black plate at the top on the body side where the door hits it. It has a slot where the rear window also slides through it.
Any idea on best place to get quality parts for this seal and part?
Thanks for info and advice, yall.
John