Advice on ‘74 Duster

Try this

Auto Metal Direct Battery Hold-Downs A-280203

Or buy a die and extend the threads down the J-bolt.
I found this on eBay says it has the correct size a 7 inch j hook for the drivers fender...the ones I had were 10 inch and I cut the excess off with a hacksaw
70 71 72 73 74 75 76 Battery Tray Hold Down Duster Dart Charger Cuda A B E Body | eBay