Connecting rod nuts

Are you sure of this? What year did this take place? MP was famous for finding the cheaper supplier and sacrificed quality to do it.

my machinist said the worst rod bolts he ever saw were in a MP package, and don’t use them.

You are thinking of the recent Mopar Performance. The old Direct Connection stuff was great stuff as was the early Mopar Performance stuff. I bought a set of Mopar Performance rod bolts off eBay and when I got ready to build my 340, we noticed someone had put cheap bolts in the package, scrapped them.