I've found some stores don't have current info and are just too lazy to make the phone call to get it. PPG, Dupont and Sherwood Williams can get info on the codes, they will be cross referenced but they can get them.
Dupont has the correct codes for single stage urathane and some base/clear but they won't have the correct name, it turns out Dupont sold there rights to the old Mopar colors to Kenworth back in the late 80's or early 90's. When I bought the paint for my Charger back in 97 it was called industrial yellow instead of Sunfire, when I asked the owner of the store about it , he told me how Dupont sold them to Kenworth.