Yup, just google the part numbers. There are several GM part dealers online.
Here is what I got them for online:
Part Number Part Name Price Quantity Total
84293345 Leaf Spring $118.97 1 $118.97
84293346 Spring $118.97 1 $118.97
Pretty cheap if you ask me and they arrived quick, in only a few days.
As for the noise, well, I had that before I swapped the leafs and still have it now (worse actually, but I have not re-tightened the bolts yet).
I "think" it comes from the shackle bolts but I am not 100%. It could be something deeper than that, maybe related to the body/frame. However, it seems to be a known issue. Per the service bulletin below, you basically loosen up and tighten up everything again:
#09-03-09-001D: Clunking Noise from Rear of Vehicle (Retorque Leaf Spring Bolts) – (Apr 12, 2016)
Some customers may comment about a clunking noise coming from the rear of the vehicle. Upon further investigation, the technician may diagnose the noise coming from the rear suspension leaf spring area.
The noise may be resolved by re-torquing the joints of the leaf spring assembly.
Support the vehicle at curb height when re-torquing the leaf spring bolts/nuts.
Note: Do not remove the fuel tank.
Loosen the shackle joint to the frame, front eye joint to the frame, rear eye to shackle joint and the anchor plate U-bolts.
Re-torque the shackle joint to the frame and to the rear eye (1). Refer to SI for torque specifications.
Re-torque the anchor plate U-bolts (2). Refer to SI for torque specifications.
Re-torque the front rear spring mounting nut (3). Refer to SI for torque specifications.
Repeat steps 2 through 5 for the right side leaf spring.
Re-test the vehicle for the same clunking noise. If the issue remains, follow the regular repair procedure.