I found these instructions from another site (not from me) I plan on using them today.
My 1999 Tracker was denied coverage for its rusted crossmember. The following is what I did with mine. If you chose to do it yourself I've posted how I did it as a guide, I am not an expert it's just information that I think will be helpful.
I purchased a new crossmember from Gmpartseast.com for $237.89 including shipping. I replaced the crossmember myself in my driveway.
I started by spraying all the bolts with penetrating oil a few times the week before I started. 4 bolts are inside the frame accessible through an oval hole in the frame. 4 bolts accessible from under the hood looking down at the crossmember.4 nuts on the lower control arm pivot bolts (I only removed the front bolts). 2 bolts for the radiator support from underneath the car, as are the 4 bolts for the steering rack not so easy to spray. 1 bolt that secures the power steering hose on top of the crossmember I just sprayed on top of this bolt.
To remove the crossmember I removed parts in this order.
1: the bolt securing the power steering hose 10mm wrench or socket.
2: 2 bolts for radiator support 12mm socket.
3: 4 bolts for steering rack 14mm socket it is a tight fit between the front differential.
4: 2 bolts with nuts for the lower control arms 17mm wrench and socket also ball peen hammer and punch to push bolts out.
5: 8 bolts securing crossmember to frame 17mm socket I had to loosen then tighten spray with oil repeat process a few times be patient.
6: using 2 floor jacks I jacked the front wheels until they were just off the ground (place jacks under the frame at factory designated position).
7: Place jack stands under frame.
8: With an assistant using a 5ft. long pipe or pry bar pry the lower control arm down on one side.
9: Now you can wrestle the crossmember out once you get past the pried down control arm your assistant can stop prying.
To install reverse the steps. Remember 2 outer rear bolts in crossmember should be in place before installing as lower control arms block these. Once crossmember was in place I did not fully tighten until after I got steering rack bolted in place. My steering wheel is slightly off center when vehicle is going straight I will look into this (check alignment).
I know I covered some very basic concepts in my explanation but this job is not that hard to do for the average person. Also I chose to pry the lower control arm down instead of climbing all the way underneath my vehicle, if you do it this way be careful you do not break it.
My Tracker has been a very economical vehicle for the nine years I've owned it. The crossmember rust issue has been a bit of a disappointment for me with GM.