Depending on the specific engine and model year, your 2002–2005 Jeep Liberty (KJ) / Cherokee 4x4 uses one of several distinct gearboxes (transmissions).
Automatic Transmissions
Most 4x4 models from these years came equipped with an automatic gearbox.
45RFE (4-Speed / Multi-Speed Automatic): This transmission was strictly paired with the 3.7L V6 engine for the 2002 model year only. It was also used in the rare 2.8L CRD diesel engine variant introduced later in 2005.
42RLE (4-Speed Automatic): Chrysler introduced this as the standard automatic gearbox for the 3.7L V6 engine from 2003 to 2005 (and it remained in use until 2012).