Welcome to the group, A couple of thoughts, First of all please update your profile with at least your state if not your town also. Second please post a pic of your tool box, a lot of snap on people here. I am told that most of their boxes has the model number stamped in the back and a date code.
If after you post a picture and if no one can help you I.M snap on Mom on here she knows a lot about older snap on stuff...
