G'day, this is my dually. It has been working in paddocks and towing down highways for over 12 years now.
4" drop spindles in the front. Then the front of the rear spring mounts were moved higher on the chassis rail. Long shackles simply bolted in. A set of Rancho 9000 adjustable shocks and it rides real smooth and handle well also.
We often load up the 2700lb truck camper and head out and it goes well.
although I have been working on a custom set of air bags, so that when backing up to a trailer I simply deflate and then raise when under the hitch, just because I am lazy and it looks so cool.