Reproduction trunk lock cylinder with keys for the 67 - 68 Mercury Cougar.
Replaces Ford Part # C7SZ-6543505-A or C7SZ-6543507-B (Glove box/Trunk lock kit).
Below are some basics about removing and replacing your lock cylinder and lock cover.
When removing the cylinder from the lock housing this button must be depressed to allow the cylinder to slide out the front of the housing. The only way to depress the button is to have the key in the cylinder and partially turned as if to be unlocking the trunk.
Any sharp object will work to depress the button or "tumbler". Sometimes the assembly must be soaked in penetrating oil for the button to move freely.
When the key is rotated back to the up and down position the button (or tumbler) will pop back up.
If you do not have a key then you will have to remove the button as opposed to pushing it down. Soaking the cylinder before trying this will go along way. Often they come right out but on occasion you will have to drill the button out.
If you do not have a key and do not want to make a trip to your locksmith then you may want to try to "re-key" the cylinder yourself. Step one is to remove the tumbler cover.
Try just removing a couple of the tumbler and spring sets and see if your key will turn freely.
If this does not work try removing another tumbler.
Once your key turns freely snap the cover back on. You will in fact have decreased your security by removing tumblers and not replacing them with the correct size of tumblers for your new to the lock key. To maintain the full security your lock was designed for you will have to take your cylinder to a locksmith for re-keying or come up with some correct sized tumblers from another Ford door or deck lock cylinder.
To remove the deck lock cover just grasp the back of the spring and rotate it a 1/4 turn.
Slip the shaft of the new cover into the housing. It will be a little stiff at first but with a dab of white lithium grease and some use it will relax and rotate freely.
Just rotate the spring and place it back in place.
Check out this video