3/4 tons springs are only different in that they don't have helper springs which do nothing to the unloaded ride. In the winter I put a big truck tire and rim in the back of mine for weight, it's just enough to help the ride a bit and the Cummins doesn't even know it's back there. I also suggest 500lbs is the easiest solution. What air pressure are you running in the back? When my truck's empty I air it down to 28lbs in the back.
.JPG){kind=link}