As the only person in the world who restores 65 to 73 decklid grilles, I thought I knew everything about them. It's somewhat commonly known that 68, like 69, was a transition year for 911s. Early 68s got the sought after aluminum case and later moved to magnesium cases during the production year. Similarly, early 68's got the 65-67 decklid and grille which were switched to the decklid style we know through '89 but with a new 3-bar grille, therefore also missing 4 grille-mounting tabs in the opening.
Owners, oddly enough, used the grille to close the decklid. The soft aluminum extrusions bent very easily and became unsightly so the grille and special decklid only lasted the latter part of 68 production and 69 years before going to a 5 bar grille with 4 extra mounting tabs for the 2 extra bars for 70 to 73. Plastic grilles maintained the 8 bolt mounting style through 89.
I have received a lot of grilles for restoration over the years and now and again will get an amateur rebuild in. I have gotten in quite a few 3-bar grilles recently, one from a known low mileage original car. It was in great shape but didn't have the dome head rivets I've seen, and made, on all other grilles. These were countersunk rivets into and flush with the bar surface. Checking carefully many of my own and other customer grilles, I found the same, also dome style, and am confident that Porsche started this new style of grille for 68 cars using countersunk rivets and then went to the dome head style rivets for 69 and later. I am totally chuffed at finding this little quirk in early 911 production.
