The correct part number is 377719-S. The clip is also show as being used for 68 and 69 200 I-6 heater hoses, and for 69 and 70 headlight wiring harness for 428CJ and 70 Boss 302 at the radiator support, 2 each. I have found no support dimensional documentation for the clip. Based on its lack of finish, I would assume it's a plastic clip. The 69 428 application shows 2 each screws 55981-S2 14-14X1/2 hex screw. In this application, the clip is drawn as a full loop. With two different applications, heater hose and headlight harness, it may exits, or not.
Jim