[SCOTI]

Changing the factory HD leaf set-up for something lighter duty will yield a difference. Which option/path you choose has different costs & effectiveness. How invasive of a project are you wanting? This is how I would imagine the ladder of effort involved:

A lighter duty leaf pack from a later model truck could be a possibility.
There are also leaf spring manufacturers that I've seen/read about offering 'soft-ride' options for lifted trucks. I'm betting there are possibly some options there that might work.

Removing the HD leafs from the current spring pack & adding an air-over-leaf sleeved bag set-up. This offers adjustability but fewer leafs = less axle wrap control (I don't think it would be an issue here, but it should be mentioned).

Removing the leaf set-up & going to a full 4-bar link system w/air bags would yield the most improvement in ride quality & the best rear axle control. BIG difference in ride quality vs a stock HD leaf set-up.

My dually has the 4-bar/rolling sleeve bag set-up. Ride is leaps & bounds better vs the 13 total leaf set-up it replaced.

Yes, mine is lowered but I planned/built it that way. It also could have been set-up for a stock height.