I just replaced the taillight bezels and lenses on my 69 442 with a new set. Originals had a threaded post inserting into the socket frame held on by a nut. The new ones have smooth posts and nothing to snug them up. What am I missing? They are fairly snug when trunk lid is closed but very loose when lid is up.

 

Your new posts haven't been threaded yet. Use your old speed nuts or whatever they call them and you will be good to go. Welcome to CO. Got any pics to share?