Stop in for a cup of coffee

Mopar Tim said
Here it is
Firewall Wiring Clip w/Screw for 1970-1976 MoPar A-Body | eBay

Ddaddy said
The ‘69 Barracuda uses the same hanger that my Dart uses...but the ‘68 doesn’t use one at all.

Interesting. Maybe there was a clip on version and somewhere around '69 they went to the new style.
At least with my current repop harness, it could definately use the support to take the strain off the connector at the ballast.