Every control rod, in every door and the tailgate, needs to be dampened. Whether that’s with insulation around them, through them or tucked in with, whatever.
Like they said, you have to track them down one or more at a time. Then keep doing it.
And when you pull the doors apart to silence the rattles, add new clips, adjust tension, add insulator rings around the lock button and do other things, spray some rubberized sound deadening undercoating inside the door cavities.
Tie things up under the dash. Make sure no extra wire bundles, plastic connectors, flasher relays, or anything else is unclipped or hanging loose.
Adjust all latches.
Adjust, readjust, re-readjust, and then readjust the readjustments, to the tailgate and liftgate latches. And when it doesn’t help, rinse and repeat.
Twice more!
Long successful, but a rarely tried cure for the liftgate rattle syndrome, is to create a couple of small L brackets to hold rubber bumpers, that screw to the opening of the top. This puts pressure on the liftgate itself when it’s closed.
First time I saw this was on a beautiful 76 that I was looking to buy with a friend in 78 or so. I immediately noticed during the initial test drive that it was probably the quietest, smoothest nicest driving Bronco I’d ever spent time in.
Owned by an employee of the Ford plant in Milpitas, he had done some interesting things. Including adding the bumpers/tensioners to the lift gate, and even adding a third windshield wiper!
Do you have the full wiper cover on? Make sure nothing‘s behind their loose. Including the wiper man. Make sure the door gaps are good, including between the windshield frame because all that stuff flexes and moves more than you think.
