What Years had Cat Converters?
 

What year did they start putting in the cat converters on these trucks.

For 2nd gens, 94 - 98 12v's were factory equipped with a cat with the exception of 94's that were manufactured before Jan 1/94. All 2nd gen 24v's (98.5 - 02) did not come with a converter but did have a resonator in place of the cat.

Excuse my ignorance here, but if the resonator takes the place of the cat does it clog up like the cat does?

I believe it was 94-98, when the 24 valve came out they dropped the cat-no clue about the 3rd gens.

No, the resonator is straight through.

For 3rd gens, 03's and 04's HOs (555) have no cat. Not sure about the SO with CA emissions.

04.5 and on, the 600 with 50 state emissions, have a cat.

If they are just straight through how did that pass EPA standards if they had already been used on previous years.

The 24 valves didn't need cats because the electronics took care of the pollutants. The resonator is there to change the sound of the engine, not to filter out smog

The resonator is not an actual emissions device and was in no way intended to take the place of the cat - it simply aids the muffler with noise control......the 24v ECM controlled engines met the 98.5 to 02 federal emissions standards without a cat because of more precise fuel management over the P-pumped 12v's.

Exhaust systems
 

I have a 99 and it has 2 ??? down there. The smaller one is ahead of the resignator by about a foot ???. Maybe about 6"or 7" across. Was down there the other day trying to fix the shake from the rear axle. I lowered the steady bearing. Put in better front springs last year because the OEM's were sagged out after a year or so. I was told by cummins in several places that it isn't there but (everytime that I hit my head on it, it either hurts or brings blood :o )

That's why I was wondering, is because I have what looks like the Cat to me, but I was always told this year didn't have them. Have never pulled the exhaust to look inside it and see what's in there.

Re: Exhaust systems
 

That smaller one up front is the Resonator.

Bigger one is the muffler.


phox

I cut both off of my '99. The front one is a resonator and the rear is the muffler. It got loud real fast!!!! Still love the sound of that truck!!:cool:

94-98 12V engines had a cat converter.
98.5-02 24V engine did not have a cat because it met emissions requirements without the cat. It DID come equipped with a resonator for noise control. The resonator on a 24V gets confused for a cat.
03 and up trucks are equipped with cats due to emissions regulations, so as the song goes, "the cat came back...".

I have a 04.5 and it does not have a cat, lucky me! I really don't know why everybody else does that I know.