Shadydog what type of setup are you running in the rear? All block, block and add-a-leaf?, add-a-leaf only, etc? If you are using the factory springs you could still install an air bag setup without any modifications. My suggestion would be to buy yourself a set of 6” replacement springs(or whatever size you need) so you can get rid of the blocks. I did this and while my ½ ton doesn’t pull what your HD does it made a huge difference. If you still don’t like the ride after new springs then I would consider an air bag setup. Adding air bags to a lifted truck with replacement springs is a little harder since the axle is further from the frame than stock but a custom bracket can be easily fabbed to make it work.