Raise the front end of the vehicle and lower the control arm onto a jack for support, then remove the wheel. Separate the upper control arm ball stud and remove the two nuts securing the control arm shaft to the frame bracket, ensuring to tape together the shims for proper reinstallation. In some cases, it may be necessary to remove the upper control arm attaching bolts for clearance; gently tap the bolt downwards with a brass drift, pry it upwards with a suitable box wrench, and then use a pry bar and block of wood to remove the bolts from the frame. After removing the upper control arm, inspect the control arm pivot bushings; if they are worn, consider having them replaced by a GM dealer, or use a long bolt and tubular spacers for removal and installation if doing it yourself. When installing, loosen the end shaft retainer bolts or nuts, position the new control arm attaching bolts loosely in the frame, and install the control arm cross-shaft on the attaching bolts. Use a normal free-running nut to tighten the serrated bolts onto their seats, then remove the free-running nuts and fit the regular locknuts once the splined bolts are seated. Install the shims in their original fitted positions and torque-tighten the nuts, starting with the thinner shim pack nut for better clamping force. Install the ball stud through the knuckle, torque-tighten the nut, align the cotter pin holes, and fit a new cotter pin. Finally, fit the wheel, lower the vehicle to the floor, and torque-tighten the shaft retainer bolts or nuts.