I need to update my post. I found that my belt HAD been changed properly at 100,000 miles. I will try and post pictures of what the belt looked like and found the mechanic from the original owner (not the Lexus Dealership) saved $1000 by taking it to a good local shop. This is why it did not show up in service records.
I had bought kit to change belt and had started the tear down when I discovered the following which led me to research further the service on this beautiful one owner Lexus, which led me to find it had been changed.
I was doing the work to change it, I pulled my Cam Inspection cover off the top left front side of the motor. Very large cover which allows a very good look at the timing belt. It still had good white print/ imprinting on the top of the belt (non grooved side), I have established that this white print (arrows, CR, LC, RC, plus TOYOTA and numbers) wears off completely at about 70,000 miles. So if I had white print, AND the belt looked good, could it still be the original belt after 153,000 miles? I concluded that no it could not be the original belt after that kind of mileage. Plus I could tell unmistakably that the crank bolt and thermostat housing HAD HAD A WRENCH ON THEM!!!!! All this evidence led me to call the original owners one more time and pull some more information out of them.
So it appears I have saved myself quite a bit of work and money here.