This is the washer for the bolts that hold on the front and rear valence.

These were used on all 6 front valence fasteners for 1970-1971.
They were only used on the 2 screws below the bumper mount bolts on the 1972-on cars. The center 2 washers on these later cars were bigger.

Material is steel, gold zine/cad plated.
ID is 5.3mm
OD is 14.82mm
Thickness is 1.27mm