Toyota Parts and Service
This link above will tell you what Toyota recommends and when they require an item to be replaced. Just so happens Timing belts are a mileage/time change item like numerous other items and for the obvious reason that rubber gets old , hard, brittle and can fly apart at or near their suggested time change interval. With the V8 being an Interference engine you can take the chance if you are willing to pay for the results!
Toyota will step up to the plate if it fails during the drive train warranty period. 90K Miles or /72 months which ever comes first is what the Dealership will tell you on a timing belt!
