My 39 is pretty squeaky but I'm going to do the following to help: sound deadener, seal the firewall, rubber mount everything like the seats glove box door etc. Hope it quiets it down!

And if all else fails open the dumps up!

56 Plaza 63 D100 step side 67 Coronet, 68 Roadrunner, 69 Super Bees, 69 Coronet 500 convertible, 70 Roadrunner Post, 79 D150 360, and a severe case of Mopar a,d,d