Replacing cat on my 2001 Ram 1500 5.9 and needed to know which to order (Carb or No Carb). Checked all stickers, Rad support and door jamb and all indicated federal. No mention of Carb, Cali, LEV... nothing so I ordered the cheaper non Carb cat from rock auto. I had someone point out to me that it might still be a Carb compliant truck and I should run a vehicle build list. I did and sure nuff it says 50 state ffv emission. My inspection stations won't give a rat a%% which cat as long as no CEL. Question is what possible issue will I run into with non Carb cat on a 50 state ffv emissions truck?

 

CARB is a California smog thing only. All other 49 states are just normal cats.

 

And that said, you don't have a carburetor either. It's mpfi.

 

You're missing the point. From what I've researched it appears that in 2001 the federal emissions got closer to CARB but not quite. However, the clever manufacturers realized that they could build one "dual platformed" emission system for all 50 states with one assembly line and then sticker the vehicle accordingly. Which is what my build sheet is telling me. So what I'm getting to, is though my RAM is stickered as federal emissions the cat underneath the vehicle must be CARB compliant to be 50 state as the build sheet indicates. That would mean that all the non CARB cats on the market for my RAM are not OEM quality replacements regardless of my sticker.

 

CARB as in California Air Resource Board.

 

Do you live in California? If not, and are probably never going to, you do not "need" a CARB compliant cat.