Hardware for securing fuse box to firewall for 70 Challenger

[Stormin']

What Hardware is used for securing fuse box to firewall at engine bay side of firewall for 70 Challenger. In other words what hardware goes on the two fuse block screws.

 

[Vaanth]

A Palnut style stamped steel nut threads onto the screws to secure the bulkhead connector.

It's a cramped space to get a good shot, but the following picture shows the nuts on my 70 Challenger:

These have a 7/16" hex size.