First, you have to get that bolt out. The best way, and it has worked for me everytime, is to wedge a 24" prybar between the skid and the frame. Hold pressure down on the skid, like you are pulling it away from the frame. This is important, you HAVE to use an impact wrench, electric or air, to remove the bolt. The bolt needs to spin faster than the nutsert (more on that) to back itself out. The downward pressure will "jam" the nutsert into place enough to allow the bolt to back out. Now, nutserts. The frame itself is not threaded to accept a bolt. There is just a round hole in the frame and into that round hole is inserted a nutsert. This is basically a big threaded rivet. On your 98, it should be a 1/2inch nutsert. These individual nutserts are available, as well as the bolts, from the dealer. They are around 7-8 dollars apiece for the nutserts and i think around 6 for the bolts. I may be flamed for this, but i replaced all six of mine with nutserts from Mcmaster-carr and grade 8 bolts and washers secured into the nutserts with loc-tite. Alot of people recommend to only use the dealer items, but I made the decision to use what i did and it has worked out ok so far. I do recheck the skid since the job was done and if i find any kind of reason to replace with the dealer items, I will. After the bolt is out and the skid is dropped, the part of the nutsert on the outside of the frame must be ground off to remove the part of the nutsert on the inside of the frame. Once the head is ground off, just pop the inside part up into the frame with a punch and hammer and just leave it or you could fish it out if you want. To replace the nutsert, put the new one into the hole that was created removing the old one. You then have to compress the nutsert. To do this, you have to make a tool. Use a 2"x1/2"-13bolt, two 1/2" washers, 5/8" nut, and 1/2" star washers. Put the tool together in this order on the bolt -- washer,washer,5/8 nut, star washer. Thread the bolt into the nutsert that is in the frame, hold the 5/8" nut with a wrench and tighten the 1/2" bolt while holding the nutsert to the frame. When it gets snugged up, the star washer will bite into the bottom of the nutsert to keep it from spinning and it will start to crush inside the frame, sandwiching the frame between the part of the nutsert inside the frame and the part outside the frame. Torque to 90ft/pds. Once it is torqued, the skid bolts can be replaced as normal and torqued to 55 ft/pds. There are writeups out there with pictures, just google "tj skidplate nutserts" and you'll find em. Good luck!