I am no expert on the designations but here is what I have picked up. Over the years Jeep would refer to their models by letter followed by a "J". General Motors (GM) does the same thing. My 89 Buick Century was a "A" body, my 2003 Le Sabre is a "H" body and the 2005 Chevy Impala is a "W" body.
It is a way the people who design and build them have a quick way to refer to the specific product. The name of the product is something the marketing guys come up with but during development they use a designation like XJ to make life easier. You remember when Jeep sold the CJ-5 and CJ-7? Also the Grand Cherokee has had a couple of designations.
Back in 1988 there were several trim packages for the XJ, they were Cherokee, Cherokee Pioneer, Cherokee Loredo, Cherokee Limited, Cherokee Chief, & Wagoneer Limited. Yes, even though it does not have the name "cherokee" the Wagoneer is a full XJ.
The Pick up version was call the Comanche, I think 1991 was the last model year for the Comanche. The Comanche is a MJ. The XJ and MJ were available in 2wd or 4wd, so either way you have a XJ or MJ.
So chill out and enjoy your XJ, most of the parts are the same you just lack the 4x4 unique items.
Is it still considered an XJ? or is just 4x4's XJ's? If so , do you guys have any 2wd members? JUst a newbie question 
