Hello all,
I have a 92 with a 351 and Auto Trans. My cats are clogged up and i need to replace them. my question is can i replace the two of them with one and still pass smog here in california.

Thanks,
Ray

Use the search button, whats why we have it, anyway the first cat is only a precat, meaning it cleans out the exhaust until the main one warms up. If you replace the 2 cats with one the only thing you risk failing is the visual.
heres my thread on the subject
http://www.fullsizebronco.com/forum/showthread.php?t=46396

That's entirely wrong. The first cat is the oxidation cat, which reacts HCs; the second is the reduction cat which reacts NOx & some other acid-rain-producing emissions. If you install a modern hi-flow 3-way cat & omit the 2nd factory cat, you should have no trouble with any kind of emissions testing.

http://www.supermotors.org/getfile/72365/thumbnail/Exhaust5.8L96.jpg (http://www.supermotors.org/vehicles/registry/showmedia.php?id=72365)

Except he says he's in California, home of the 'known to the State of California to cause cancer' people.... smog there is VERY strict.

It may be that in California you will have to have the exact factory replacement parts in the exact factory location to pass; at the very least you will need a definitive answer from the smog folks before you buy any parts.

I had my exhst changed to a high flow cat and flowmaster muffler...no problems with smog...and I have to take mine into a test only station.

Except...No exceptions. When they first enacted those laws, they were very restrictive, but now, any aftermarket emissions parts sold there are CARB certified.

That's entirely wrong. The first cat is the oxidation cat, which reacts HCs; the second is the reduction cat which reacts NOx & some other acid-rain-producing emissions. If you install a modern hi-flow 3-way cat & omit the 2nd factory cat, you should have no trouble with any kind of emissions testing.

:doh0715: I'm sorry, I guess I shouldnt take all info I learn to be true. I'll double check from now on.