OTC Tools OTC 7491C Upper Control Arm Knock-out Tool. Removes the inserts on upper control arm alignment brackets. Services 1989-current Chevrolet and GMC 1/2-, 3/4-, and 1-ton 2- and 4-wheel drive trucks, and 1990-current all-wheel drive Chevrolet Astro and GMC Safari vans. New, improved design has a self-centering knock-out for full punch removal with less tear.