Did this K20 come factory with catalytic converter?

[ButchM]

Juke
The best answer to any questions asked about engine originality is "I was told the engine was been rebuilt" nothing more.
Butch

 

[ButchM]

Juke
Your truck is referred to in the GM parts manuals as an "03" body (2 door fleetside). The option label in your first photo shows it has the LT9 5.7L/350 engine and C6P heavy duty chassis.
Hope these help
Butch
This page from a 1991 GM parts manual shows the codes "K2" and "03" for the 2 door 4WD pickups.

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This page in the parts manual shows the K2/03/LT9/Calif emissions (3/4 ton, 2 door, original engine) has a single exhaust with no cat.

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Lighter duty trucks with the 305 or the LS9 350 did have the cat.

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The front page of the manual is below.

 

[Ricko1966]

And if you start arqueing technicalities,instead if just trying to make them happy,they are going to discover your truck isnt right. Once they discover your truck isn't right,then the real fun begins. If they are willing to pass it and ask no further questions,put some cheap cats on it and go away a winner. Going to another inspection station is just a gamble maybe they won't want cats,but might find 6 other things,1 being the wrong engine,that by the book,won't pass. Go in act stupid,say nothing and do what they ask if it's piddly stuff. A pair of cheap cats is less than 150.00 I've paid more than that in late penalties many times. Here's another nitpick for you,you convince him it's a heavy duty emissions truck,no cat's required, then he looks at you and says well a heavy duty emissions truck has to have the correct air cleaner with emissions sticker intact. If you don't have it, good luck finding one cheaper than cats.

 

[ButchM]

Ricko is not off base with his recommendations. If you have a place that says you just need "this" (cats, or fill in the blank) to pass; you may be better off taking that route, assuming its not stupid expensive. If the guy wanted to be a butt it would all have to be near like it left the factory.... missing a sticker, sorry, you have to have it.... wrong type air cleaner, same... This thermo valve, that no one has in stock or no longer produced, is not working and needs replaced etc, etc, etc. You could win a battle and lose the war. Some/ many places will look that it all "appears" to be correct, in place with no obvious damage (hence, wanting to have cats) run the sniff test, if its below limits, you are golden.

Also, contrary to what some have said, if they know where to look closely and are knowledgeable, a 305 has a few observable differences from a 350, casting marks on the ends of the heads, harmonic balancer are quick checks with a flashlight and mirror. Often the engine code on the right front block pad and casting numbers at the block left rear are quick checks in a full size truck.

This leads back to if you have a shop that says (in writing) that you need "this" to pass. I'd be for making them happy and getting the smog slip.
You may also be dealing with a guy that would be happy to have the correct information and be willing to work with you.
Going stock would also require putting a single exhaust system on the truck. Only you can determine the best course and it would likely depend HUGELY on how you present it to him.
G'luck
Butch