I see that I can either get this: https://www.rockauto.com/en/moreinfo...122084&jsn=940
or I can get a universal cat. I'm just not sure which one better suits my needs.

I'm replacing my cat because I had an injector that was stuck open, causing a flood of fuel to hit my cats. It ran incredibly rich and I'm pretty sure the cats are fouled as I can only smell gas from the exhaust, and especially next to the cat.
How do I know if I need the air tube kit?

 

I'll let you have my wife's black / white tuxedo house cat for free! Litterbox & a bag of food included for the price. Must pick up. May provide some yowls during your drive. :-)

 

I have read your posts from day one. You sure seem to like looking for something to replace. It takes a long time to destroy a converter .I doubt your converter is bad. They are pretty durable. Have you tested it to see if it melted down?? I bought a car with a melted down converter which blocked the flow of exhaust. That car barely could make it up an incline.If you are still smelling gas, it is not from the converter. You are still running rich or you have a pinhole leak somewhere.. Any fuel should have burned off very quickly.

 

x2

 

1) When I got the car, it had rotten vacuum lines, a base timing of 18 BTDC, a bad ground, a bad purge valve, etc. Who knows how long the car was driven with all these problems that likely masked the stuck open injector. It could have been months that the car was driven with a stuck open injector. Are you telling me that isn't enough time to ruin a cat?! I've put around 1k miles on the truck already since I got it.
2) The FPR is working properly, and so are the fuel pumps. I could do ANOTHER fuel pressure test, but I doubt I'll find anything. I already did another vacuum test and couldn't find any leak anywhere. I also don't smell the fuel in the engine bay.
3) The smell is strongest right next to the cat. I don't smell it at all in front of the truck, or on the driver side. As soon as I get next to the exhaust I can definitely smell gas with a bit of sulfur. And when I walk to the cats, forget it. It's like being at a gas station.

 

get it running properly, and then rediag. you would know if you had a cat plugging up

 

Re-edited my comment if you wanna see the rest.
Also, a bad cat doesn't mean a plugged cat. Just saying

 

Raski, I just looked underneath the car right after cold starting it, and could clearly see exhaust coming out of the bottom of my rear cat...

 

Is there a hole in it? Is one of the flanges leaking? Is the air pipe connection broken or leaking??

By the smell of sulphur, that tells me your converter is alive and well. You need to address the rich running engine. The raw gas smell is likely coming from a fuel or evap line. That converter would be glowing red if there was an issue with it and raw fuel dumping out the exhaust.

 

I'm an idiot who confused his muffler for the rear cat. The muffler is leaking and has holes. The cats have never reached glowing red. The metallic line that goes from the EVAP Canister to the rear tank does appear to have wet spots, and so I assume that it is in fact leaking. I also just found that there's something wrong with my charging system, and will be making a post of that soon.