Thanks for all the good input guys and lots of anti-rust methods/products to choose from! I remember when I used to use Extend on small rusted areas which worked well but when I tried the NAPA aerosol it did not.
While the POR-15 rust system seems like it may be best it sure seems awful pricey and labor intensive. I'm leaning towards the Eastwood systems and while not cheap it may do the job.
The below internal frame coating looks like it may be a real good investment since it seems like on a lot of my Jeeps the rust is coming from the inside out. It may also be good for spraying up in the rocker and door drain holes if it doesn't clog them up.
The rust on the underside of my 2004 isn't as bad as the photos rdkendrick in Cinci posted. I was under it last week using a med-course wire wheel on a drill for cleaning off the leaking muffler seam before I brazed it. I tried the wire wheel on one of the many spot welds rusting and sure seemed like it took a long time just to get part of the paint off while the rust was still there. Wonder if after cleaning I could just use a hand wire brush for slightly cleaning the rusted areas off and then spray or brush on rust converter?
If I'm not going to use the 4 cans of black undercoating I have I would rather keep the bottom stone white like it already is since I may not do the whole underside or may miss some spots. I bought a small pricey can of "Mopar PW1 Stone White Clear Coat" at the dealer about a month ago designed for touch up. Does anybody know of a good aftermarket top-coat paint which comes in this color in an aerosol can and not so pricey? Not sure it would contain a clear coat and would I also need to spray this on top of it?
Thanks bradywgn71 for pointing out the part I asked about is the rear upper control arm. I feel kind of stupid for not knowing that but I'm new to WJ's and have only had D35 axles before, rather than the 44, along with separate upper control arms rather than one piece. Also the parts list didn't have a very good diagram of it.
While hard to get to the upper control arm is probably one of the most rusted parts on the undersise. It's going to need scraped/wire brushed off before I even think about spraying a rust converter on it. The rear drive shaft is also super rusted with chunks of rust on it. I would guess I should also clean this off and spray rust converter on it? Can you also just spray rust converter on the axles w/o cleaning them off? Sounds like I'm going to be using so much rust converter I should buy it in liquid form, like a quart, then use a trig-sprayer for applying it.
Sure wish I could get my WJ up higher since I have a nice pressure washer for blasting everything off. It would be better if I could somehow do away with the wand part in certain areas. Would do this after applying a pre-clean or marine clean. It doesn't help I have long running boards on each side which makes the bottom even less accessible. I'd just take them off but my small wife likes them for getting in/out and this will eventually be her dd.
Here's some photos of the underside and just love living in the salt/rust belt! Poor design from the factory where they caulk shut the rocker drain areas in front of the rear tires. Since a bunch of dirt/small grit there I dug it out and sprayed with galvanized primer. Need to do it again where I removed the caulk.
Also another one of the pics show behind the front tire. You can see the rust stain which looks like it's coming out of the inside of the rockers. I best check to make sure these drains aren't clogged. Sorry for the blurry rear control arm pic but was shooting it blind and too close.
Thanks for any input! Sorry for the delay in posting but had to get my son off to S. Cali where he's moving to. He's 3/4 of the way there in hauling a big trailer w/his 96 4.0 XJ.