Thanks for the message!
Unfortunately, we do not have an aluminum radiator specifically for the automatic 2001-2005 Lexus IS300. We are apologize for any inconvenience this may cause. You could potentially use that radiator in your automatic vehicle if you were to purchase the optional transmission cooler (part number MMTC-U). I have provided a link to the product page below in case you would like to take a look.
Please feel free to contact us directly at firstname.lastname@example.org if you have any additional questions!