Where to find rust on a 97-06 Jeep Wrangler TJ LJ 

I bought an '05 3 years ago, Had rust in all the body spots you mentioned and more. But the frame is solid. Having a new tub, fenders, windshield frame and tailgate put on. While the body was off the frame was cleaned and had 2 coats of POR15 put on along with stainless brake lines. Had it all Raptor liner sprayed in close to the original color. Picking it up soon.

TJ frame caps usually aren't, in the midwest, something to completely walk away from. A properly repaired frame is as strong as a factory frame. TJ frames usually don't get to the point of rot where anything but the bottom 30% of the frame is bad, which is why caps work so well. The salt and water sit and pool at the bottom of the frame, and the frame doesn't fill all the way due to sidewall drainage. Many frames that require repair have the same solid painted steel it had when it was made in 97-06. Caps aren't a bandaid, as long as prep work and rot is *cut out*. I have seen many frames with caps BOLTED to the old frame. That's obviously a bandaid. I have also seen caps welded on without cutting out the old rot. That's also a bandaid, usually before trying to sell it. A qualified fabricator + welder can make most TJ's with frame rust back to original spec. Many of the TJ's you'll see don't have a frame that disintegrating by the time the owners catch it. It's bottom floor and 10% of the side wall. That's a lot different than say an OBS Chevy frame that will likely crack by the time an owner knows it's "that bad" instead of have the bottom eaten through. Really good pointers on the body though. Few people understand why body rust happens, and it's hard to find people who understand it's not just rock chips. It's almost always really, really poor drainage design.

The best part about being into Jeep restoration in the NW is that they outlawed salt on the roads here. It may rain all the time but its fresh water so it never gets too bad.