IF you're really looking into building a ZJ or WJ that will fit 35's and is up for rockcrawling you should check out mallcrawlin.com, just beware as they are kind of like the pirate4x4.com site but for Grand Cherokees so they don't take kindly to noobs or noob questions, BUT you WILL find alot of usefull information. As many have stated earlier on this thread there are probably better rigs out there for what you're trying to do but IF you are really set on getting a Grand Cherokee for this you might as well build it right. And of course doing that requires A-LOT of time and or A-LOT of $$$$ but if the end result is getting something you like and makes you happen then it's probably worth it. Below is a pic of a ZJ rolling on 38's on DANA 60's and coil overs and this is probably a mid-range "extreme rig" compared to some of the other "extreme rigs" some people are running on this site...

Enjoy,
Fred R.