Dumb question, but do you need a 3/4 ton? You could put in lighter springs, but that sacrifices load carrying ability. I have a friend who got so sick of the ride in his 3/4 ton that he just drove around with a heavy load all the time to soften the suspension up. He took a bunch of steel stock and loaded it in the bed, it really did smooth the ride out, but sacrificed fuel economy big time. You could look into a new seat that is squishy and shock absorbing? Not really sure, good luck.
Kyle