There are two things to look at first for the clunking. GM's smaller Blazers are notorious for eating upper ball joints. It is common to have to replace them every two years. This design is the more common non-load-carrying ball joint, so all that is needed to check them is the suspension system can not be hanging down when the truck is jacked up. It has to be supported with jack stands under the lower control arms. You might be able to get some in and out movement when you push and tug on the top of the tire, but it is the up and down movement that is more common. Use a pry bar to try to force the control arm to move up and down, then watch for the play in the joint. If that does not make sense, the best approach is to have the steering and suspension systems inspected at a tire and alignment shop. The people there can show you how to check the ball joints and what to look for.
A lot of GM trucks use a variation of Chrysler's torsion bar front suspension system on their four-wheel-drive models. GM's rear attaching points are mounted on rubber blocks, and it is common for those to break loose. The bars cannot go anywhere, but the metal blocks bounce up and down. You will hear the clunking when they come down and hit the cross member. You need a pry bar to lift the arms up, and just a couple of wrenches, to replace the mounts.
Saturday, August 12th, 2017 AT 10:06 PM