So today on my way to work my 2000 Blazer made a loud thunk on each of my 3 left turns that I had to make. Never happened before and they were pretty loud. Then while I was driving around after work (still thunking on left turns), it started to do it while making rights as well. Probably drove a combined 25 miles all day. The noise seemed to be directly under the truck as well, not really near engine at all. Now when I am shifting it in and out of park into either drive or reverse to attempt to hear whats causing it, it is doing it constantly. One big loud thunk while shifting and a couple loud thunks in a row while making either a right or left turn.

The transfer case is getting a pretty big jolt while I had my head under there and had a buddy shift it in and out of gear. Is that my problem? Could it be anything else? Could something like that have taken a sh** like that this quickly? Any suggestions/advice would be greatly appreciated.
,

 

Take a good look at the motor mounts and trans mount. Those could possibly be causing your clunking.