Richard,
Go back to the PGCA home page at
www.parkerguns.org and on the left side of the page is a list which is made up of web page links. Click on some of those and you will find information on how to ID your gun.
In particular, click on "Parker Identification", I think it will help. The other links are interesting too. The FAQ has a list of Parker books, "Grades" has pictures and be aware that they are small thumb pictures but if you click on the thumb picture it will expand into a full picture with good detail