Hey, idkaboutthis,
The good news is that (most) lowering springs can be rotated if you lift the wheels off the ground. You'll see the pocket in the perch when looking up at the bottom of the perch. Stick a finger in there and the end of the coil should be 1/4" from the flat vertical end in the perch. If the gap is bigger, unload the rear end and rotate the spring (watch that the top isolator stays in place) until the coil end is in the desired position (1/4" gap to the perch end). Repeat on the other side. Lower the vehicle and go for a test drive.
Another possibility is that the springs are in upside down. Tighter coil is the one that goes on the top.
The last spring possibility is that the coils are contacting each other ("binding") over bumps. If this is the case, you'll need to get some sleeves to slide on the coil(s) to quiet things down. Forum member "SugarMouth" had a metallic noise coming from the rear and coil bind (contact between coils) was the problem. Here is a link to
his thread.
Before you look at any of the three things listed, check that all fasteners are tight and properly torqued. Then take a good look around the rear and see if something is loose or is making contact now that the rear sits lower. Look for a witness mark where rubbing or contact is occurring. Use a floor jack and raise the rearend to decompress the springs, then lower the rear (quickly) to see if the noise can be generated.
If you want to check one side at a time, then put the rear up on jackstands and then put a floor jack under one tire, remove the floor jack on that side, and raise/lower the free side to see if the noise can be generated. Repeat to check the other side.
That's about all I can suggest for now.
HTH.