Cant get key switch out of housing, on a 1974 chevy pick up.Trere are no screws or clips visible.

If you mean remove the ignition tumbler from the steering column, you will have to remove the steering wheel and lock plate, then you will need to remove the turn signal lever and screws, and then pull the turn signal switch up and out of the way, you should then be able to see the housing for the ignition tumbler down in the steering column. Look at the tumbler housing and there should be a small slot towards the end of the housing that you can put a small standard screwdriver into and depress a locking latch that is built into the tumbler. When this latch is depressed you will be able to pull the ignition tumbler straight out of the column.

If I remember correctly you need to put the key in the lock and turn it (can't remember if it's to on or accessory) Some also have a very small hole near the key. if you have one you need to push a small allen key or wire into it to get it to release. Been a long time but I think I remembered right!!