There are brand new 58/59 stepside tail light housings on Ebay for $49.99 each. That's a little pricey, but it's a simple, correct fix. Install them with pop rivets through the two holes that are already there.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!