As a by product of another discussion and a recent visit to a local yard I thought I would post a few pictures of original bumpers, dating practices and location of those dates to help others. Need to find some 71-3's as well as fill in a couple of holes - when done I'll post in a formal article in the Library
65-66 Front bumper. Normally the area where the date is is accompanied by a difference in the plating in that area (not polished like the rest of the bumper) Marked - 10 12 M5
Early service replacement Marked - 10 26 M6
67-68 Rear bumper Location ins on the back side between the license plate light mounting holes Marked - 11 2 M7
69-70 Front bumper Location ins on the back side near the center of the bumper Marked - 70 M 76
69-70 Rear bumper Location ins on the back side between the license plate light mounting holes M9 66