I spent the first Saturday in quite some time in the shop today, knocking out the steering rack replacement. It was a wet, 33 degrees, and sleeting out, so overall not a bad day to be getting greasy under the GX. The bushings in the old rack were totally shot (seemed to have happened last time I went off-road), leading to the rack moving around quite a bit and making a lot of noise in the process.
Overall the steering rack replacement was not that bad. I used a Cardone reman rack from Rock Auto (~$250) and the quality was very good. It was completely cleaned/coated and had brand new inner tie rod ends.
Pulling the old rack took around 2.5 hours. This included jacking up the GX, and removing the skid plates, sway bar, inner fender splash guards, front differential mount bolts, oil filter, and the inner tie rods ends. The steering shaft was definitely stuck on the rack. I used an air hammer and was able to work it off over around 10 minutes. What really helped was putting the air hammer in the gap on the steering shaft (where it slips over the connector on the rack). This really opened up the splined connection and allowed me to get it off. However, the high pressure line connection to the rack was pretty rusty, and the flare nut was practically welded to the line. The rest of the line looked questionable, so I just cut if off. Once the rack was unbolted I also loosened several wire loom brackets and was able to wrestle the rack out within a few minutes.
After a trip to O'Reillys to get a new high pressure line ($143 - I ordered it at 10 AM and it was at the store by 1 PM) and a few other things, I had the new rack in. As with the old rack, I removed the inner tie rod ends to make the install easier. I also spent some time getting the rack as perfectly centered as possible before re-connecting the steering shaft. I attempted to also get the steering wheel perfect, but must have been 1 tooth off as I broke the clockspring when I tested it later

. My airbag light is on and the steering wheel audio buttons are not working - but I found a used OEM one for $30 on eBay and already ordered it.
After bolting everything else up (sans skidplates), I gave the GX a quick redneck toe-in alignment:
After re-filling and bleeding the power steering fluid, the Lexus drives great! The steering is very tight now! It had more slop in the old rack than I thought it did. Also, the hard steering issues (which many attribute to the U-joint in the steering shaft) are totally gone. It is getting an actual alignment on Monday.
Overall this is not a bad job. If everything is in order I think it could be a pretty easy 4-6 hour DIY. It took me around 8 hours but I spent some extra time dealing with the new PS line (parts store run). Also, my battery crapped out after maybe 2.5 hours with the key on ACC - and had also gone dead after a couple of hours listening music while camping late last year. So I also spent around 1-2 hours trying to jump the GX (not really possible in a 1- car garage), trying to swap the battery with our Subaru (terminals are on the wrong side....), and finally running out to just get a new battery.