Yea, a bit rare indeed.
http://www.toyota-4runner.org/3rd-gen-t4rs/195830-original-owners-only.html Been fun the past 14 years! I have a brand new < 5000mi) OEM radiator installed and monitor temperatures EVERY day! So far I plan on leaving it the way it is as my temperatures are staying in range. See photo below. I've read a lot of pros and cons on the site about doing it both ways. I think the installation is th emost important and using the correct fluid. Install it so the return line back to the tranny is on the bottom. Dual electric fans are on my list of mods to reduce the engine load and reduce temps.
Living in the NW I don't experience a lot of stop and go traffic but I live on a mountain with a 3 mile climb and I drive with the OD off and ECT on. The temps go up. Water goes up into the 190's to low 200's on a HOT day and ATF temps will push about 180 upwards of 210. I experience similar temperatures with mild off road excursions.