I'm not sure how to tell the 247 and 242 apart, but they came in the ZJ and WJ Grand Cherokee's. The 242 looks a lot like a 231, but with a little longer tailshaft.
One way to tell if the donor Jeep is AWD is to look at the indicator plate on the transfer-case lever; if it says '4-hi, N, 4-lo' it's AWD. (No way to lock it into a 'locked' front and rear split either, another strike against them IMHO) if the plate says '2-hi, 4-hi, N, 4-lo' on it, it's the NP 231 and if the plate says '2-hi, 4-part time, 4-full time, N, 4-lo) it's the NP 242.
I don't know of any write up on it, since most folks want to swap the 247/249 out for the 231 or 242. Sorry.
Is Calmarkid2002 correct? Are you thinking of upgrading a 2wd to a 4wd? It's difficult, and labour intensive, but easier on an XJ than on any other SUV/truck out there. You'd be best advised to either sell your current vehicle and simply buy one like it with 4wd; your next best bet would be to purchase a 'donor' vehicle and swap the front axle, and transmission (along with the transfer case and driveshafts) into your Jeep. You'll need to cut holes in the floor, and set up the linkage to activate your t-case, but it's a doable project with time, effort, tools and cash.