Your passenger side looks like its bent over and up as there shouldn't be a space between the lower support the bolts for the skid plate go into and the frame.
Granted, tweaking the bumper mounts should get the bumper back on.
I would imagine someone chopped those off to try to bend it back closer to where it should be.
Explains why your parts aren't matching up perfectly though.
Sent from my SM-J337V 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