Sure is. The president of my chapter has a 99 escalade layin frame on 26s. But all i can say you dont know what you are getting yourself in to if you plan to go that big.
i know WAY back (like 6 years of so ago) truckin or street trucks one had a navi on 22's layin running board. he kept the AWD setup so I'm sure 4x4 is possible. It was maroon with chrome 22's. A good name shop did it I believe. I don't remember last week so im suprised i remember that much.
unless you have alot invested in it, i would sell it and get a 2wd. cheaper that way in the long run. 4x4 usually gets more money anyways. make a bit just swappin.
It cost almost nothing to put this kind of 4 by 4 on Air............give me few days and i will put some picture.........it take about 1 hour to do the front and you ll bounce like a pro.......
i am just gonna find a 2wd frame for mine and lay it out on some nice 20s or maybe 22s,and try to keep my heat and a/c.i am thinking swapping frames will be less work,with access to a lift that is.