Previous owner stated that they changed the timing belt at around 98k it didn't have a sticker but took his word for it. To ease my mind I took of the cover to check the condition... It looks in great shape and is a Gates brand, made in US, belt... Does Lexus use Gates as an OEM part?

 

Mitsuboshi is the OEM belt if I recall correctly. Looks like your timing belt was changed.

 

Agreed, Gates is a good aftermarket brand belt, Honda uses them as OEM, and likely others as well. Did the PO mention if the water pump was done as well?

 

Negative, he did not but I did notice that the radiator and hoses appear to be new and still have aftermarket part# stickers on them. Maybe they were replaced at the same time as the belt? If so, I've gotta assume he did the pump also.