I recently ordered a pair of OER grill inserts for my '68 Firebird 400. The part numbers ordered were 9793723 and 9793724, which I've checked multiple times are the right numbers for a 1968 400.
For each one of these grill inserts, there are 5 mounting points. Three u-clip fasteners along the top to bolt against the upper bumper reinforcement, and two pegs along the bottom, which fit into the grommets of the grill-to-bumper brackets.
However, when I try to mount the grill inserts to the upper bumper reinforcement using the three u-clip fasteners, the lower half of the grill insert looks like this:
If I instead only use the two grill-to-bumper brackets, I get much better lower fitment, but the upper half of the grill insert is no longer flush, and looks like this:
When the bumper-to-grill brackets are used, and the lower part of the grill sits flush with the bumper, It is not possible for me to use the three u-clip fasteners to mount the grill insert to the upper bumper reinforcement, as the holes in the upper bumper reinforcement are about 1/2 an inch above, and 1/2 an inch behind where the u-clip fastener is:
Most of the stuff I've bought from OER has been pretty true to fit. This doesn't look like a fitment issue that just requires some minor trimming, it's as if I have the wrong part entirely. Both the left and right side grill inserts which I bought suffer from the same problem.