I have one of these that has never been used. Not sure how to tell if it's by Williams. It is marked USA on both sides and is stamped 01210. Measures 6 13/16" long. PM me with any other questions. Mike
How about taking the lock out of the box and taking it to a locksmith. He should have no trouble picking it and will be able to make you keys for it.
I have a friend who did this for me with no problem.
Mike