Just some pictures for now of the Daystar shackles part # KG60002 to fix the rear end sag on the blazer. I have since also installed an add-a-leaf kit (long leaf) since the rear springs had started sagging again after about 4 years of running the shackles.
The shackle removed:
This is laying under the truck and looking up at the gas tank + shield. The top of the picture is towards the back of the blazer. You'll see a small ding on the diagonal edge of the gas tank (left side of the pic) where the bolt was hitting the tank and I couldn't remove it.
I didn't have to remove the whole shield. I just had to undo the few bolts towards the back of the blazer and then loosened the two back gas tank strap bolts to let it move down a bit so the bolt would clear.
Here's a side-by-side comparison of the stock shackle (right) and the daystar (left).