My cats have been rattling for a long time on my 2002 Escalade, I happen to find a set of low mile caps off another 2002 Escalade. They are both completely different and I don't understand. From my Google searches, everything seems to match the new to me cats and Y pipe. But that is not what is currently on my Escalade. Anyone shed some light on what the heck is going on?Everything on my existing setup looks Factory which is what I don't understand. The Upstream O2 sensor bung is in a different location on the new to me set, and there's some sort of a pre cat diffuser on them as well. This all jives with the Google images that I'm finding for a 2002 year set up. What the heck is on mine?