The Standard Servo has been used for nearly 20 years. There are (9) different valves available. The lower the number the "easier" your car will steer. The torsion bar size is stamped on the end of the valve and on the adjuster nut. If your servo is stamped with a letter (M or L) this means it was made before 1995 and may need service. It is very important to change your power steering fluid regularly, as servos do not like any type of foreign debris. If the servo is damaged in an accident you may experience a violent wheel shake. To repair a servo it must be balanced properly to make sure it does not pull left or right therefore it is necessary to send all servo repairs to Sweet Mfg. Uses 401-50610 & 401-50611 U-joints.