Whenever I start out I hear and feel a clunk noise from the rear end of my 2010 wrangler sport. Anyone know what it could be?

 

I have this same issue, It's your spider gears, something was set up wrong and they have chew'd themselves up. To conf this you can pop your rear dif cover and take a look. More than likely they look like someone took a chisel to them.
I think my factory LSD did this to mine.
Should be covered by warrentee.

 

Thanks, will definitely have this checked out...

 

I had a clunk upon starting, from the rear. It turned out to be the right lower control arm bolt on the axle end was loose. I had adjusted a spring a few days before and I suspect I missed it when I was tightening things down.