Well, you haven't mentioned that before, but obviously they haven't done a good job if it still poking out to one side... It's no difference where you do the job, it's how you tighten everything up. I've mentioned 4 post lift as an easy option, but you can use a pit, heavy duty axle stands, etc.Excuse the ignorance but what difference would the 2 post lift make? They still (so they told me) did the bolts up on the ground with load on the suspension.
For polybushing you need:
Leaf spring bushes for both ends, all 4 will likely be in the same package.
Chassis bushes for the shackles
Antiroll bar bushes will make no difference, but if you upgrade antiroll bar, it will make a noticeable difference in body roll. I went for 24mm Whiteline anti roll bar and it transformed how the Caddy feels on a twisty roads, roundabouts, etc.
Yes, you can also use the shackle blocks to further stiffen everything up https://www.caddy2k.com/forum/viewtopic ... 22&t=40266