I had 110K on my 2001, I ordered the kit on a Mon night and then,on that Wed night, with the parts IN THE MAIL, driving on a city street going 35mph with no stress on the engine, 10 teeth sheered off the timing belt. In the process, whatever raw fuel didn't burn in one of the cylinders - no Timing Belt working properly means no spark, no spark, no combustion, no combustion = raw fuel going out the exhaust valved directly into the cat. Which, in turn, fried the first cat on the left side. Of course, as soon as the engine died I knew what it was, I had timing belt on my mind. But, on the lighter side, had it arrived the weekend before it likely would have been put on the shelve in the garage for a few weeks (until it cooled down a bit in in AZ as it was September). When I disassembled, I was ammazed at the horrible condition the belt was in. I would suggest no more than 5-years 80K on the TB as the 3.3 runs so hot it must rot the timing belt. I don't know if being in AZ matters since the engine temp is much hotter than the outside temp.

So, word to the wise and not so wise. If you have 100K on the belt, get to work!

And, while you're inthere, I'd replace the knock sensor by moving it up and out from under the intake manifold, replace the water pipes under the intake manifold and of course, replace the water pump, belts, cooling hoses, little hose all the way inside there (see thread on the topic in this forum),actually find ALL cooling hoses you can find including heater hoses (be careful with the heater core connectors - they are plastic) and even check your radiator.

I'm one who would rather be proactive and replace stuff regularly than wait for it to go.

If you need links to the timing belt directions, here are some:

http://www.maui.net/~mauitom/Xterra/xterra.html

The other links I had seem to be disabled but I have PDFs for them if you email me, I have a yahoo group setup with lots fo how-to pdf's I collected from the forums just in case they disappear. It would be nice if there was a way to store them on this site.