Striker169, Since your car is a Grandé, it would also have the Mach 1 style deluxe door panels. There is a metal grommet with a felt insert the lock knob passes through that you need to check. Over a period of time the anti-rattle felt deteriorates and allows the knob to rattle. A lot of the aftermarket knobs were a different diameter from the Ford units and were responsible for more rattles to chase down.
Don @ Ohio Mustang Supply sells both the correct grommet (different from the standard door panel) and the knobs. Don is a Forum member/vendor here and has taken care of all of us. https://www.ohiomustang.com/store/order_page.asp?itemid=712
https://www.ohiomustang.com/store/order_page.asp?itemid=1675