My friend bowed out of working on the Jeep because he couldn't pin down the source and does not want to just throw parts at it. I got a recommendation for a 'come to you' tech. He also believed it to be in the CV axles so replaced them yesterday. There is still some noise but it has diminished. I found that the rear differential bounces up and down and is sometimes hitting the underbody. Any ideas on what to check next?

Also, were planning to go on an 800-mile trip in the next couple of days. The tech said the Patriot is safe to drive (behaves fine otherwise) and the noise only happens intermittently. I'm generally a worrier and even so I'm leaning towards going. We've been hearing the noise for well over 1000 miles. Any thoughts on what to do?