Harness Connector Nuts - what size?

[1968rt]

1972 B Body firewall connector nuts. Cant find the right size. help

 

[Nacho-RT74]

7/16 hex head

 

[1968rt]

7/16 hex head

The problem is the threads. Seems to be a coarse thread like a sheet metal screw.

 

[72RoadrunnerGTX]

Palnut stamped nut originally, having a sealing compound within.

https://www.forbbodiesonly.com/moparforum/threads/sealer-in-firewall-pal-nuts.80692/