Welcome to the site. I have one that is 575XXX with a lever boss code "B", that makes it a 1950, and another with a lever boss code "D", 646XXX, making it a 1952. So, I'd put yours between 1950 and 52. I think Davids book has the serial list, but, I just woke up and don't feel like going down stairs to check. Someone will be along shortly to give you more accurate dating, Joe.
