So as far as I remember, there is only ever one agency that has the cars right there at T3. I think that is Hertz currently but it changes every few years based on which agency wins the tender to be at T3. All others you take a shuttle bus to get to them.

According to IAA website, Hertz, Avis, Eldan and Budget are at T3,. While dollar and Thrifty take a shuttle bus.
https://www.iaa.gov.il/en/airports/ben-gurion/car-rental-companies/