Thanking you Walter for your reply. Yes I know what numbers mean and I question if any one has seen 1 and 3 stamps. I have not. Let us say some one ordered Ithaca that was made for stock 2 and 4 and he wanted 4 opened up to 3. Would Ithaca had over stamped the 4 with a 3? Or just let the 4 stand with no additional marking done when choke was opened up.?