Did you use stainless steel bolts? Pull the studs and put sealant on them. I they aren't stainless they will rust shut.

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