Installed this over the weekend on my '18 Diesel Sedan.
I tried a few different variations of 2017/2018 and Sedan/Hatch all with the 1.6 and LT trim and the current version of the Chevy Accessories website says it fits some and not others. There is no option to toggle between automatic/manual trans. When it does pop up there is only one part number (84105410) and it includes the sway bar.
The upgraded parts codes were:
Sway bar: AAJ9, #39000784, 29mm x 4.5mm wall
Front Spring: AA7N #13479752
Rear Spring: AAWV #13366701
The stock parts were:
Sway bar: AAKP, #39005088, 28mm x 4.5mm wall
Front Spring: AG7 #13367034 (Diesel/Manual specific it seems)
Rear Spring: AAVB #13366696
Oddly, I can't find the upgraded front springs or stock rear spring anywhere online. And it looks like the sway bar is probably the stock unit from the Volt.
The bar isn't that terrible to install, but my opinion would probably change quickly if I were doing it on an older, rustier car. Lots of steps but they're well documented in the included instructions (also available online.) The only step I skipped was removing the lower ball joint. Since I was doing front springs as well I just removed the coil-over assembly which served the purpose of separating the outboard wheel assembly from the body. Working on the garage floor and with half-shafts still attached my subframe couldn't drop far enough to concern me with completely un-plugging ABS and steering rack wires. The front springs and bar took me about 5 hours on my back with jack-stands, basic hand-tools, a rented spring compressor, and a small pneumatic impact for the shock top nut.
With a tape measure and bubble level I couldn't see any alignment changes worth having addressed. Despite having the tape and string out, I got completely unscientific with ride height, but from top of the tire to bottom of the fender lip I went from four fingers to a tight three on the front, and a lose 4 to a tight three on the rear. I expect it may well shrink another .250" or so over the next few months.