I would say YES it is. 1999 was a change over year for the front axle in XJ's. Some had the HI-Pinion 30 as all earlier XJ's, while from mid/late '99 on had the same LO-Pinion as the wranglers have.
Even then the mounting points on all axles either LO or HI where the same. There was some differences in TrackBars from year to yaer and model to model, but the lower mounting points are the same. As far as I know.
CW