I have a 97 tj..from ny....my frame is holding up well and so are my body brackets..what isn't is my tub...the drivers side polys have sunken up flush with what was my tub support channel/frame.QUOTE]
If your channel has rusted bad enough to let the bushings sink in you have a little bit of fab work to complete. The mount bolts thread into captive nuts inside the channel. Some of these are probably missing and others are probably so rusted that they'll shear off when you try to remove them. I have never seen a TJ that rusty (and I'm from Mass, where we use the most salt of any state. Here, if there is the chance of one snow flake they send out four salt trucks to find and kill it) . Keep in mind that the channel has an indent in it at each mount which "cups" the rubber bushing. So, the channel was not flat across when it was new. Also, body lifts put even more stress on that channel so you want to make sure it's good and solid before you lift it. I did a 1 inch body lift on my TJ for the exact same reason - to make a little more room under there so I can clean the salt and sand out. I think the bolts were 3/8"-16 thread, but that's going to be the least of your worries until you make some new channels up. There are eleven body mounts on the TJ, two of which are way up inside -just about over the rear axle (the eleventh one is under the radiator. Best of luck - John