Catalytic converters: does your square have them?

[Keith Seymore]

1975 cats became standard on cars and trucks under 6000 GVWR,

I can confirm that our '75 1/2 ton swb pickup had a catalytic convertor. It blew the bottom out during a long decel on a freeway off ramp, scattering the pellets across the roadway.

It was a bit dicey for a few seconds until we cleared the debris field.

K

 

[DoubleDingo]

I have a 1983 GMC K3500 with an auto trans and a 454. The whole exhaust was stripped all I had was the manifold. After multiple muffler shops denied my request to only run mufflers I finally found one that would do it.
In North Carolina. They told me it had to go back to the way it came from the factory to be legal and to pass inspection. However When they were looking up parts and diagrams to redo my exhaust nothing was found for an 83 k3500. I know the 1500 with the 350’s had them. The muffler shop eventually told me that it must have never came with cats. So the truth is I don’t know. But my truck is over 30 years old so it doesn’t need to be inspected. Stupid laws

Being a 3500 most likely no cats

 

[TPISly-C10]

originaly 6.2 diesel so not cat there...no cat here!

You must be registered for see images attach

 

[Craig 85]

I have a 1983 GMC K3500 with an auto trans and a 454. The whole exhaust was stripped all I had was the manifold. After multiple muffler shops denied my request to only run mufflers I finally found one that would do it.
In North Carolina. They told me it had to go back to the way it came from the factory to be legal and to pass inspection. However When they were looking up parts and diagrams to redo my exhaust nothing was found for an 83 k3500. I know the 1500 with the 350’s had them. The muffler shop eventually told me that it must have never came with cats. So the truth is I don’t know. But my truck is over 30 years old so it doesn’t need to be inspected. Stupid laws

Your truck never came with them. My K30 is the same set up as yours with California emissions and it never ran cats. Check your fuel fillers. They should be the larger style for regular fuel, not the small unleaded style. Also, the gas gauge should NOT say Unleaded Fuel Only.

 

[K5ride]

My 75 Stepside came with single exhaust with catalytic converter. California does not smog 75 and older so I replaced it with dual exhaust / no cats.

 

[Goldie Driver]

This is what I thought too. The inspection guy I go to said it depends on the whole antique, classic, or regular plates. I told him my 82 didn't have cats when I purchased it (also the glove box lid is replaced so I don't that list of otpions). He said antique plates are the only ones I could get if a stayed with no cats. Of course he would say this after I had the exhaust redone.

I was flying by memory, but this seems to confirm it for Texas :

https://www.emissions.org/loc/texas-emissions-testing/

Aged based only.

Antique plates have a 2K per year mileage limit- dunno if they check - but IIRC only requires inspection once every 5 years.

Classic plates don't offer that, but the safety inspection is only 7 bux and I can drive it as much as I can afford gas for it.

 

[78C10BigTen]

You might be onto something. 35 year old single exhaust looks brand new, the dirt notwithstanding, on the car, but the true duals on the truck not so much. I would like to see duals that old on a vehicle that’s driven at least three days a week.

My (catless) true duals have been on my truck uninterupted for about 4 years driven daily.and are still in great shape.

 

[SirRobyn0]

My 81 with 350 came with a single pelt type cat back to a muffler and then dual outlets that came out the right side behind the fender. When the warranty was up the whole exhaust from manifolds right to the back was removed and headers with duals installed. All nicely stored in the attic of my garage just in case?? With a distributor recurve and riching the secondary jets mileage went from 7 mpg to 13 mpg while pulling a car hauler trailer loaded.

My 84 was a Portland, Oregon truck from when it was bought new until I got it. I don't have emission testing, but Portland tests 1976 and newer. My truck is setup exactly like yours except the pellet cat was replaced by a modern honey comb cat at some point and has duel outlets but on the drivers side. I did not realize the dual outlet muffler was factory.

 

[Kim Burke]

Mine had all the stock exhaust intact including two cats and x pipe. Built in Norwood assumed it was a CA spec’d truck. I wish I’d taken pics before removal. This is the only exhaust pic I’ve got.

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[drware]

My 86 K30 got it new had the little factory headers without cats the pipes had heat shields around the pipes back to mufflers Replaced mufflers 10 years ago but pipes still good. Still drive it every day. Got down now having it painted now

 

[discuspro]

So, Austin (williamson cnty) can be tricky it seems. I am in the process of getting my 81 C10 inspectable and no cats (current status) got me wondering... Also, I don't have the stock air cleaner, no EGR, long tube headers, no TVS. I've had people say if they look under the hood they are taking you for a ride and I should be fine... but I am not resting easy yet...

 

[donnieray]

I live in a NC county that don't do emissions inspections but if cats were standard on your junk then they do a visual. Most towns have places that uh, don't notice if they are missing. I have true duals and dynaflows or magnaflows on my stuff. My daughter lives in a NC county that smog checks everything from 1990 up. Also cool about NC is anything 35 years or older don't have to be inspected!

 

[DoubleDingo]

I remember when I used to have my 65 smogged every 2 years. Was glad when they changed that rule

 

[John-Ryan]

I was flying by memory, but this seems to confirm it for Texas :

https://www.emissions.org/loc/texas-emissions-testing/

Aged based only.

Antique plates have a 2K per year mileage limit- dunno if they check - but IIRC only requires inspection once every 5 years.

Classic plates don't offer that, but the safety inspection is only 7 bux and I can drive it as much as I can afford gas for it.

Right on the money! Took ours in for an inspection and was pleasantly surprised at the $7 inspection. Caught the mechanics drooling over it and they told me to check back in when I do some work on it.

 

[DoubleDingo]

Right on the money! Took ours in for an inspection and was pleasantly surprised at the $7 inspection. Caught the mechanics drooling over it and they told me to check back in when I do some work on it.

When I take in my '81 C20, the guy that owns the smog testing station always comments on the truck. He tells me every time to hold on to it because they are rare to see and easier to pass emissions.