Here is a 512 page manual for the 403 International Harvester combine.  At the bottom of the pages near the front, it indicates it is revision "6-66" which I assume is June 1966. So its 60 years old.  It also indicates that it is revision 2.  Pictures should tell you a lot about the condition of the manual.  Thanks for looking good luck and happy bidding.  Payment within 5 days please.