What is the metal used to manufacture the 2000 4Runner exhaust? Since is is not showing any rust, I believe it may be some type of stainless?

Under normal conditions, what is the life expectancy of the catalytic converter? One web site states the cat. can be efficient beyond 27 years under normal wear and tear. I am having problems with my insurance adjuster who wants to depriciate the complete exhaust system of a 2000 Toyota.

Not sure on exhaust materials, but I have talked with plenty of people that have had troubles with cats on 3.4L engines for some reason. They seem to be getting 120k on them, then clogging issues start to surface.