Te clunking is usually a result of the bushings wearing out. They are replaceable, but I believe the rack has to come out to do it. Following copy and paste is just part of some comments posted by a veteran GM suspension/steering master tech on another forum (Traverse) which uses the same components.
the loud/hard clunking noise heard on model years 2010 & prior is due to steering gear mount bushings. the replacement bushings are made of an updated compound. service procedure requires r&r of steering rack/pinion to replace. as bad as the noise can sound, it does not present any safety/operational issues in my opinion.
the loud/hard clunking noise heard on model years 2010 & prior is due to steering gear mount bushings. the replacement bushings are made of an updated compound. service procedure requires r&r of steering rack/pinion to replace. as bad as the noise can sound, it does not present any safety/operational issues in my opinion.