This is an ancient thread but I am looking for seat rocking/movement information. Just recently acquired a 2009 Tahoe Hybrid and both the front buckets (drivers and passenger) have noticeable play. Just a slight shift movement to **** you off when driving it LOL. I narrowed it down to a pivot arm rivet that is part of the seat track. It does not appear to be an easy fix as it looks like it would involve drilling out the existing rivet pin and replacing the rivet with a shoulder bolt or something similar.. I know there are probably many thousands of owners out there that have this issue. I probably just have not run across the right forum yet......................sorry for dredging up a "dead thread" from 4 years ago but maybe someone will see this and chime in? I have a shop full of drills/presses/grinders/welders etc. I just do not want to attack until I see what others may have learned.