crawl under your truck, lay on your side and stare at the gas tank. Situate yourself so you are by the drive shaft looking to the driver side of the frame rail. if you follow the fuel line, there is a black canister thingy, this is the fuel filter. It's kind of tucked into the frame rail, and it blends in a little bit but you will see the fuel line enter and exit. It is kind of cone shaped on one end.
I had my 01 seqouia with 90k on it over at a good toyota independent service center doing some A/C work on it and I told him to change the fuel filter and he said he wouldn't even bother...I asked why, and he said he's taken tons of them out to replace with new ones and he said the old ones are clear and that he can even blow through them...just a thought.