Now I'll tell you what I found. I'm quite embarrassed but since everyone responded with true concern, I should give you the opportunity to laugh at me.
It's hard to tell exactly where noises come from when you're driving. I knew the noise was way in the back. The noise always occurs when I drive out of the driveway and make the turn into the road. As I was sliding myself under the bed of the truck to do the inspection, I grabbed onto the trailer hitch and a noted a clunking sound. It's a class III hitch which I leave in the receiver 365 days/yr. and it's usually rusted in place. Last Summer or later, I broke it free, cleaned it up and shot a lot of grease into the receiver. After I got done today looking, I yanked the hitch out and drove in and out of my drive without any noise. What an idiot. Something that simple. So have your laugh; you've earned it.
I appreciate everyone's replies and your advice on shocks will not go un-noticed.
Thanks