The brace shown in the diagram above listed as 13-64-72 is what the 1970 specific Coronet brackets tie too. (brace 13-64-72 also used on 1969 and 1970 Chargers)
The outer ends of that brace (referred to occasionally as a bow tie brace) bolt to the bumper brackets, but all 1969-70 Chargers & 1970 Coronet bumper brackets have the mounting holes for the brace.
Due to the different bumpers & valence on the Chargers, while that brace is the same, the front bumper guards and the adapter brackets are 1970 Coronet models only, Super Bee, Coronet R/T, the 4-doors, station wagons, etc.
I may still have a set of the guards and brackets here somewhere..........
I would be interested if you have them. They look good on the Bee's, the rears not so much
