Well all my jb weld cracked and let my diff cover seap again in less then 2 years. I live in the same environment you are currently in as I in southwestern PA...
The Eastwood frame coating didn't work for me either. Maybe it's just me, I used it in an arch I sprayed it into rust when I went back in to fully fix it a year later it was rusting..
I basically repair 3rd gen 4 runner frames as I hobby and even rebuild them from rot damage.
You other methods sound very good. I just know from experience that it is extremely difficult to clean out the frames if they are full of dirt or debres or rust. I even do all my frame repairs [plating ]on the inside of the frames.
In the rust belt, I basically try to remove the frame holes to keep the salt water etc out and when repaired I paint for an indicator then coat with a rust inhibitor. My build thread is full of actual frame repairs in these frames.
Have a good semester as I am looking forward to seeing you build/ repair thread when school is out.
Sent from my SM-A505U using Tapatalk
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7 3rd gens listed in the build thread (2 are parts mobiles)
Build Thread:
https://www.toyota-4runner.org/3rd-g...os-builds.html
Brillo's Bucket Fluid Ex changer:
https://www.toyota-4runner.org/3rd-g...ml#post3358086
Sparks Plugs Wire and Coil Information:
https://www.toyota-4runner.org/3rd-g...on-5vz-fe.html