Adding the 4th arm is for your serious off-roaders running over size tires and 1-ton axles. Although it is not needed in most cases (Rigs with factory axles), it does benefit on high horsepower rigs that require the added strength.
This kit will include everything needed to make your current Standard 3-link into a 4-Link kit.
Heims and hardware needed.
WELD ON passenger side crossmember mounting brackets.
Passenger Side Control arm.