You shouldn't have to. If they are grinding, make sure the teeth on the flywheel are good. Also, make sure the solenoid on the starter isn't failing. One last thing, were there any shims on the original starter? To be honest, to me it sounds like a bad solenoid. If you are getting the same aftermarket part, you may want to try a different brand. You shouldn't need to get one from GM. Try a different brand and make sure the teeth on the flywheel are in good condition.