CTS — Sigma II (2008–2015) → 2008 ✓ Factory-verified internal ⛭ GM factory document — 2008 cadillac cts rpo code list, p.1.
STS — Sigma (2005–2011) → 2007–2009 ✓ Factory-verified internal ⛭ GM factory document — 2007 cadillac sts rpo code list, p.1. ⛭ GM factory document — 2009 cadillac sts rpo code list, p.1.