I've talked to (interrogated) Bestop, 4WD, 4WP, and Mopar. Nobody knows the answer, BUT they all state the differentiation occured in 03 and supposedly based on specs. The stated interchangeable ranges are 97-02 and 03-06. I'm "told" and have read several places that there are slight measurement differences at the windshield (supposedly 4 degrees back in 2003) and the rear cargo area is 1" longer from door closure to rear.
04 Sahara, with a lift, some stuff, and a few things, on some 33's, blah, blah, blah.
A perpetual work in progress. Too much to list, not nearly enough to matter.
My RigRater Score: 387RRv1.0 with a BOA of 18.92 (and just how exactly is this going to help me over that big arse rock?)
Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut.
~ Ernest Hemingway