Most T56 shifters are very easy to swap. I don't know about the Caddy specifically but in my GTO the only tough part was getting the old shifter unbolted from the trans because the bolts were all the way up under the trans tunnel (and they used Torx head bolts). I had to actually pull the trans crossmember so that I could get a hand around the trans from below to get to the front two bolts. In Camaros and Corvettes, once you get the console off it's just a matter of removing 4 bolts, lifting the old shifter off, dropping the new one on, and bolting it down. Hopefully the Caddy is similar.