One problem related to driveshaft has been reported for the 1999 Lexus RX. The most recently reported issues are listed below.
Early failure of transmission after following maintenance schedule and changing fluid every 30k miles. Transmission failed while drive in the desert 75 miles west of salt lake city, utah. Transmission replaced at roseville Lexus, the replacement would fail to go into drive when the gas pedal was push after stopping causing many near collisions from the rear during heavy traffic, second transmission was replaced finally, but the stabilizer bar mounts were left disconnected and rubbing on the brake lines and drive shaft. Incidentally the first replacement transmission was missing three bolts which attached it to the engine. The quality of work by this dealership was very poor and unsafe to the owner. The second transmission replacement was poorly done and the drive shaft came out on the right side tearing the seal and leaving fluid everywhere. This dealership caused more damage to the vehicle and left it in unsafe condition which could have caused injury to the occupants.