I received this very helpful answer earlier this week for my 2003 Sequoia with interference engine: "At the most, you should consider replacement every 9 years/100k miles. Always a good idea to check it for signs of dry rot every other year or so depending on climate just to be extra safe."
Does this interval also apply to my 2001 4Runner with non-interference engine?
The 3.4L V6 in that 2001 4Runner is non-interference, so no damage will happen even if the timing belt snaps. With that said, it's still a good idea to change it at the recommended mileage interval. If the belt snaps, you will not be able to re-start and drive the car, which would be horribly inconvenient. If you plan to keep the car a long time, you may as well just change the belt when you hit the mileage interval to avoid a big hassle.
Thanks for the quick and thoughtful response. I assume you mean it would be a good idea to change the belt in my 2001 4Runner at 100K miles as outlined in my question above, but ignore the time interval of 9 years as recommended for my 2003 Sequoia.
Yes it is a good idea to change the timing belt on that 4Runner every 90K-100K miles - it should also say the exact interval in the owners manual. And yes I would just go by mileage.