So both the doors on my 75 H/O (Cutlass) rattle while driving. I've adjusted the king pin so they are flush at the opening OK but the drivers door rattles (which I think may be the glass rattling inside the door) but the passenger door seems more solidly shut yet it rattles once closed (while driving) and I can tell it's on that kingpin? Neither pin has any kind of plastic covering on (which I understand some do).! It's like the lock in the door has too big of a hole that the kingpin locks into. The hinges appear good and the doors aren't sagging! The inner door panel - especially on the drivers side will be coming off at some point as it's not attached right and that door was replaced at some point in the car's 50 year life span!
Bob

 

Your door striker should have a nylon bushing around it. It will rattle without it. You can buy the bushing or whole striker bolt with bushing.
After I rebuilt my door hinges along with new strikers, most of the door noise went away.
Jeff

 

Thank you

 

Got those bushings and the door shuts like the car was brand new. Thank you!