for 3rd Gen GS you need three torque values as it is a sealed tranny.
Drain plug : 20N.M
Overflow plug: 20N.M
Refill plug: 39N.M
BTW, personally both plugs I never use torque wrench but need a new washer for sure.
Attention: Contact first with your local Lexus dealer double check all the values above before you go ahead.