Check out the "official lift/ leveling kit" thread in the Suspension Tech forum. That will give you all the information you'll need. Aside from that, Rough Country and Readylift are some of the more popular leveling kits used on this site.
With the exception of the Bilstein 5100 leveling strutts, they all pretty much do the same thing. I'm a fan of lifetime warranties so I look for that. ReadyLift makes a great leveling kit. I have the CCM kit (which is cheaper) and it has served me exceptionally well. Also, take a look at the threads that TELORVEHC mentioned. There is a ton of information there.
Whichever one you can get the best deal on. They all do the same thing, with the exception of leveling struts. If you plan to install it yourself, look for a lower strut spacer like Rough Country or Top Gun Customz.
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