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Models before 87 production:
Remove steering wheel.
Remove 4 screws securing lower column trim and remove trim.
There is a slot in the side of the housing for access to the locking pin of the cylinder. Turn the key to the locked position and press this pin, the cylinder should slide right out.
Models produced after 1987 :
These cylinders require the key to be turned approximately 60° from the locked position and insertion of a wire approximately 2.1cm into the hole beside the key. A paper clip works well. You may also find it easier to put a bend of about 10° in the end of the wire, insert the wire with the bend facing the outside of the housing, once fully inserted, rotate the wire until the bend is facing the key hole and slide out the housing.