Im certain the individual who posted this question has already A) solved the issue or B) sold the truck by now. In either case the solution that I found and performed on my Yukon over a year ago ( no issues to this day) was buried in an ocean of YouTube videos. I didn’t want to do the grease fittings method, as I found in another video. The method I used is shown in the attached video. Some guy did this on an F-150, (EXACTLY THE SAME CONCEPT) and it worked perfectly for me. See the link to the video.
Hope this helps someone.