Can you install a 70 grille in a 73 front end?
 

I was wondering if you can install a 70-71 grille in the front of a 72-73 front end? It is a non-rs front sheet metal.

yes.
rick k

^^^ what he said.
I believe the only difference is 73's have a little more support bracing in the radiator support area because in 1973 the DOT increased the safety standards for front end collisions. All the other front end parts are interchangable. 73's just have a few additional support pieces.