This past weekend I changed the air shocks on my 2007 Escalade. After digging through RPO codes and checking a few websites I determined the correct part number for me was AC Delco 580-449. That's for the 2007 Escalade Base with RPO codes Y91 (luxury edition), Z55 (air ride and electronic chassis package), and P56 (22 inch wheels). The best price I could find shipped to my door was through Amazon. The shocks arrived and took less than 1 hour using power tools to install both sides. The most difficult part was removing the inner fender liners to gain easy access to the top shock bolts.
Others have reported issues with knocking the ABS wiring loose and ending up with an ABS light after replacing the shocks but I didn't have any such issue.
My next project will be to free up the secondary latch on the spare tire.
-Rod