71 fenders have a notch for the grill. 71 were used as replacements.
You do see cars with one 70 and one 71 fender at times as well.
It is a simple fix to wed sheet metal in and closes the holes up.
The adjuster {bumper} is also in another spot but that is not glaring as a U shaped hole.
I would fix that if switching from a 71 to 70 grill