Just want to help anyone out by telling how I removed my bench seat headrests out of my 1970 Duster 340. These headrests have one long (RH) and one short (LH) chrome post.

Raise the headrest all the way up. Get a spray can of Kel's Heavy Duty Pure Industrial Grade Silicone (or equivalent) and install the straw tube. Now, insert the tube 1-2 inches down the backside of the right-hand post aiming straight down. The retainer latch inside the seat is on the RH post of both the driver's and passenger's headrest. Give it 2-3 squirts of spray. Be super careful NOT to get silicone on any vinyl, it MAY discolor certain types. Now, wrap the headrest pad with a couple layers of foam and secure with 2 or 3 bands of masking tape (to minimize the chance of damage). Push headrest down a notch and grab each post just below the pad (NOT the headrest pad itself) with your hands and quickly go upwards. One or two attempts should have the headrest out of the seat. It's simple, easy, fast, and it worked for me without any damage.