Can't really find a straight answer online, and when I look them up on Rockauto it almost seems like they are interchangeable. Anyone know for sure? Won't have my truck with me for another week and trying to gather some parts for a tune up.
Had my buddy go out and look for me. He swears up and down there are only 2 upstream, one off each manifold, and none post-cat. He said there are two bungs but they are blocked off and look like it was done from the factory. He's done a couple different swaps and builds so I assume he's right. Does this seem right?! Everywhere I look online for parts lists 2 different part #'s, the 2 upstreams and 1 rear are the same, and then the other rear is different because of wire length.
Completely stock until I got it. Intake, Nelson Tune, and single magnaflow muffler. He said the bungs were about 10" from where they cut the pipe to weld the muffler on. So I don't think the guy that put it on would have messed with it. He also said whatever they used to block the bungs off were equally as rusty as the exhaust tubing itself, so I doubt it was done recently.
Edit- Also not throwing any codes and had it scanned anyways just to make sure. All is clear. If there were 2 missing where they should be, shouldn't it be throwing a code?
I'll have to look at mine when I get home, but I'm thinking it's got two before and two after the cats. I know the ones I have put transmission in all had 4 (2 before and 2 after the cats).
He said he looked around for a harness to plug them into and didn't find any? I don't know man, I'm pretty stumped. May call a dealership Monday and see if they have any insight.
"To the OP you only have 2 upstream. My truck is same way. I was told due to the displacement of the 8.1 it puts the engine in a different catagory? and there are not enough 8.1s to worry about monitoring emissions? somthing to that effect. No problems , less sensors to buy."
Haha well, I got around to the plugs/wires/o2's today. 122,143 miles on the odo, and EVERYTHING was factory. The o2's took some time to get out but they budged. Forgot to take a picture of them but it looked like they were dipped in flour. I'll let the picture tell the story on the plugs. Missing one because i dropped it and bent the prong. Needless to say it runs 100% better and my idle and low rpm miss is gone.
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