fish321us

So, I recently just got a 2002 Suburban from my father in law who passed away. Apparently at one time he changed the catalytic converters with some experimental ones since he worked at K&N. Recently when I went to get it smogged (in California) they failed it because they couldn't find the CARB number on them, lucky me. So, now I'm looking at replacing them, but as I'm looking around, it seems that 2002 is some special year where the converter y-pipe (CARB compliant) is super expensive, but ones for 2001 and 2003 have more options on price. I guess my question is, I would've thought that 2001-(at least)2005 models would all be the same. What, if anything, makes the 2002 different than say, a 2003? I'd like to just get a 2003 y-pipe to save some money, but obviously I don't want to buy it if it's not going to work.

Any insight on this would be appreciated.

Thanks!