I don't know the part number but good for you tackling the project. Mine blew (2015 Big Horn) and I took it to the dealership thinking it was something else. It cost me about $2500 to fix as they had to cut off the factory bolts and in the process melted the DEF tubes (I think). So be very careful of those tubes and you may be better served to drop the exhaust and fix it on the bench.
Did you get the AEM update within the past 4 years or 48K miles? If so it should be under warranty and replaced for free at the dealership. Or did you just remove the nuts yourself?