DIY: Transfer Case Actuator Repair
Transfer case leak - Page 12 - ClubLexus - Lexus Forum Discussion
The above to link might help with your transfer case.
Link #1 deals with a common 4th gen issue. If the 4x4 is not engaged frequently it locks up and just won't work. To fix this you have to open the actuator cover- little plastic box at the back of the transfer case. If the previous owner opened this up to get the 4x4 working again he may not have sealed the box correctly and it will leak. I had this issue as the rubber O ring on the lid didn't want to seat correctly. Took a few times taking it off before I got it positioned correctly. If you do this be prepared for gear oil to spill out, maybe 1/4-1/2 cup, also one of the gears may or may not want to slide out. Hard to tell from your pic but typically when gear oil leaks of course it sprays backward and not so much forward/onto the back of your transfer case, so the actuator cover may not be it. When mine leaked it did not get on the transfer case but only showed on the actuator box itself.
If that's the case if may be leaking from the actuator arm seal. See link #3 - it's from a Lexus forum but I believe the parts are all the same.
I would clean it all up with contact cleaner and get a better idea of locating the source of the leak.
Regarding your back tire. Just guessing, but personally I doubt any of the front end/rack or rear gears or shocks diagnosis. Your frame is bent and you already know it's been in a rear end collision. Frame shop and/or have a buddy drive behind you see it's visible. I 've see more than a few trucks going down the road visibly sideways, the rear clearly not tracking straight. Makes me wonder what their tire budget is.
Hope you get it sorted. I have 290k on mine V8 like yours owned since new and has been a reliable rig.