Actually just picked up my 4runner from this place this AM.

They capped the entire passenger side mid section, replace parts of the frame on both front (behind bumper, near radiator) and at rear bumper, sand blasted the entire bottom and undercoated (think super thick tarry stuff that takes a while to harden)

$2300 and it took a week. This is actually my 2nd 4th gen that I got for a song, which is why I wasn't too worried about spending the $ for the frame repair/coating)

ETA-weird thing about this one was passenger side frame real rusted, holes flaking etc. Driver side nearly perfect (at least for the northeast). Tech said the AC drain line was responsible.