Apologies. 72 car. All are Dearborn, right? Spring time frame build by the serial number.
Directly in line with the shock tower, when viewed from the fender/tire area. With the fender on, there is a small ledge or lip poking out. I have seen *2F123456* stamped here. I’ve also seen it stamped in the same area but under the fender, not visible with fender on. This area would not be affected when changing either front or rear apron.
Neither side shows any evidence of a number. I’m going to take a look again after some paint stripper and scrubbing.