I believe its quite a bit of work.
Mine makes the thunk when its really cold- and when turning the wheel fast.
(actually quieted down a bit, after I did my preventative maintenance on a bunch of the front suspension around 145,000).
But- as stated by a GM tech on here--- the thunk sound- is not detrimental to driving.
But if it annoys you... get it repaired.
I will simply wait until the Rack and pinion goes out. I can live with the occasional thunk.
There is something in the front end that has too much play. I got a wheel alignment and the traverse drives straight but depending on turning the wheeel the steering will be off center. If i turn the wheel the other way then the steering wheel will center back up. So there has to be play in either the outer tie rod ends, rack and pinion / bushings or even maybe the control arm bushings.