Going through this now! I'm still confused. Lol!! The previous owner had a new cat installed prior to my purchasing, passed Smog and sell went through, no issues. First time I had to have it smogged, all went well. Last year I failed for missing one cat, and for the one I have on, being the wrong one for my engine family???? Another thing that pisses me off is how they label it on the Smog test results. They label it as "tampered", which sounds malicious. Anyways, im trying to locate the correct part numbers so I can get this handled. By chance can anyone provide me the part numbers and approximate cost? Aftermarket preferred of course. I've searched but cannot locate them. Am I supposed to have two cats? Are they sold separately or are they sold together? Has anyone successfully had the dame problem corrected? This has been a nightmare. This truck is going to be my son's for college and I want to always hold onto it. I love it and just want to get this put behind me. If anyone can help, I would truly appreciate it. Thank you all for your help, and the information on this site. Always very helpful folks on here and just knowing that help can be found and shared with each other is fantastic. It's truly a brotherhood type of feel here and I sincerely appreciate the information. Take care all and I pray to hopefully hear from any and all that can aid me.