My research shows that the front bumper/front shield studs were A-chassis parts A-17766 (rear stud) and A-17767 (front stud). And they were the RGJS design 3 (5/8" square at inside of frame). This is for AA's starting 6/30 for the conversion to the new "B' suffixed body types (82-B, 76-B, 85-B)
These have the following measurements:
A-17766 rear stud 2-3/4" frame contact point to shield contact point.
A-17767 front stud 1-7/8" frame contact point to shield contact point.