I went through shockwhorehouse.sukit.....best price, but lagging in customer service. i guess if you want the lowest prices, you pay for it in other ways
the rears would help, but it's not all your shocks. I would say its about 20-30% shocks....the rest, your leaf springs with the HD spring pack. you cannot expect to tow heavy, and get a cush ride all from the same spring pack....there are some mods that can be done to the stock spring pack outlined over at dieselplace.com
some other guys claim that the shulastics make a big difference.....im not gonna dup +- 400 bucks to find out...im happy with what I have
BTW,,,shockwarehouse.come has a discount code for dieselplace.com members...in their thread