Hello gregsproat from Texas. Welcome to Air Forums. This is a very good website for you and your 63 Trade Wind. Hopefully someone will help you.
I have a 66 Trade Wind. The entry door lock was made by Bargman, mine is a model number L-100, which is a rotary door knob style lock. I rebuilt two of the Bargman L-100 locks to fit the unique Airstream "set back" of 3 1/2 inches. I do not know if your trailer has a cast aluminum door frame that is the reason for the odd ball set back dimension. Mine has a cast door frame.
I purchased a used Bargman L-100 on e-bay at an exorbitant price. These old locks are rare and thus spendy. But I needed the parts, and a Schlage $50 lock would not work due to the odd ball set back dimension.
I see there was one for sale on this website, but alas it has been sold. Here is the old link so you can learn a bit more about these old locks. Search the classifieds and you might find another one.
And search the internet and see what you can find. Old Airstream door locks can be a problem. Just another challenge for the vintage trailer enthusiasts.