Ok, I have an 05 quad cab SWR duramax with 6.5 bed. I'm towing a 5th wheel trailer weighing about 12k lbs and a hitch weight of 2500lbs. The truck squats but not terribly. When going over rough highways it "bounces" a little, has anyone helped this by replacing shocks or even upgrading to 1 ton springs? I realize that air bags or such could help, but they will just work when "bottoming out" , I'm looking for what's best for "all the time". Any suggestions from those towing ? Thanks

Shocks wont help with the squat but they will help with the bounce. I recently took off the factory shocks and replaced them with some Bilstein shocks I got from Kennedy. I was amazed at the difference when pulling the 5ver. I had been considering some kind of system for the pin box the bounce was so bad. After changing the shocks the ride is much more under control. As far as the squat - air bags if you want to be able to adjust, otherwise timbrens.

I have a set of Air Lift Super Duty tow bags with an on board tank and compressor. The airbags along with my Bilsteins really smoothed out the ride of my truck while towing, I couldn't be happier with the way my truck tows!