To remove and install the radius arm, first raise the front of the vehicle and secure it with jack stands under the frame, placing a jack under the axle. Disconnect the lower end of the shock absorber from the shock lower bracket on 1983-89 vehicles or the lower stud on 1990 vehicles, then remove the front spring. Next, take out the spring lower seat and stud from the radius arm, followed by the bolts that attach the radius arm to the axle and front bracket. Remove the nut, rear washer, and insulator from the rear side of the radius arm rear bracket, then take out the radius arm and remove the inner insulator and retainer from the radius arm stud. For installation, position the front end of the radius arm from the bracket to the axle, installing the retaining bolts and stud in the bracket finger tight. Place the retainer and inner insulator on the radius arm stud, inserting the stud through the radius arm rear bracket. Install the rear washer, insulator, and nut on the arm stud at the rear side of the arm rear bracket, tightening the nut to 80-120 ft. lbs. Tighten the stud to 190-230 ft. lbs., the front bracket to axle bolts to 37-50 ft. lbs., and the lower bolt and washer to 190-230 ft. lbs. Finally, install the spring lower seat and spring insulator on the radius arm, ensuring the hole in the seal aligns with the arm to axle bolt, then tighten the axle pivot bolt to 120-150 ft. lbs. Install the front spring and connect the lower end of the shock absorber to the lower bracket on 1983-89 vehicles or to the stud on 1990 vehicles, torquing the retaining nut to 42-72 ft. lbs.