All of the above info is correct but only applies to 4 1/2" bolt pattern stuff.
I found a 4" bolt pattern 9" drum 76 Dart last year. Car was a 4 door /6. Story I got was 4" b/p stuff was used on 4dr /6 cars only as far up as 76.
Never say never with any of the older stuff...
As earlier mentioned I've never ran across a 4 1/2" bp with a 9" drum...