Actually, you need to leave the stock Pitman arm installed. Yes, do not installed any kind of a dropped Pitman arm. Older Jeeps needed dropped Pitman arms but '97 and newer TJs have a better steering geometry design and do not require a dropped Pitman arm.
In fact, installing it would cause Bump Steer, a problem you don't want where the steering is "bumped" left/right as you drive over bumps/dips in the road.
The only time you want a dropped Pitman arm with the TJ's steering system is if the driver's side track bar has had its mount replaced with an aftermarket dropped track bar mount.
It goes like this for a '97 or newer TJ...
-When you have an aftermarket dropped upper track bar mount, you need a dropped Pitman arm. Dropped goes with dropped, they must match.
-When the upper track bar mount is not dropped, neither can the Pitman arm be dropped. Undropped must go with undropped, they must match.
You can't mix dropped and undropped where the trackbar and Pitman arm are concerned.
And I don't care if the kit came with a dropped Pitman arm. Put that dropped Pitman arm in a Craiglist or eBay ad and make a little $$$ on it.