Barn find 72 340 duster

Here is a few pics of the exhaust hangers from the Duster. a few things of interest here. First is the 10,000 day calender date which is 99201. If I have interpreted this correctly it would be 12/31/69. Both are the same date code. Very early for a 72 model year. Few other details are black phosphate bolt and natural finish on the bracket itself. The other thing is the undercoating on it. This were installed before the undercoating of the wheel wells. My car is not a full undercoat car, only the wheel wells and what over spray that is seen on the bottom of car from that application. A little more investigation will be in order before I can tell what other items were installed on car under body prior to application of the undercoating. These show signs of pre-undercoat installation. Hard lines, brake and gas, exhaust hangers, and rubber brake lines.