Front Leaf Spring bolt size?

1971 Dodge Dart Swinger

I'm not at my car but need to pick up some things while I'm out and about. Does anyone know the size of the front bushing bolt for the leaf springs? I believe my car has 7/16" bolts since it was a slant 6 car but my new leaf springs need a 5/8" bolt so I'm going to replace the bolt and enlarge the hole in the front bracket. Thanks in advance!