Our control arms are going into a '71 Charger R/T. To prep for the new arms, measure the distance between the lower control-arm bumpstop and the frame with the car sitting at normal ride height. This will provide a reference for later ballpark settings. Jack up the car and support it with jackstands by the framerails, allowing the suspension to drop. Remove the brake calipers to get the brake line clear of the upper ball-joint stud.