Way too good of a deal to be true.
I own an 06 X that I bought from the dealer on April 30th 2006 and I still owe more than that.
I hope for your sake that you really are getting this jeep at such a good price but don't be sending any money until you see and touch the actual jeep.
One of the latest scams I have seen on craigslist is a woman who works on a cruise ship and wants to sell her ex-husbands jeep for really cheap just to get rid of it. As always it is out of state and needs to be shipped to your city regardless of the listing that said the vehicle is IN your city.
Here is an answer to your actual question about running 37" tires on the 2006 TJ-X.
You will need to upgrade your axles, braking and steering as well as install at least a 4" lift or a 3" and highliner fenders. Then you will need to gear your new axles to run that size of tire without trashing your engine. You will probably have to upgrade your transfer case and install a slip yoke eliminator. And don't forget to upgrade your drive shafts.
Soooo, after spending $3500 on the new jeep you would spend another $5000 (or more) upgrading it to run 37" tires.
Why is there so much space down here?