Exhaust sensor help please - Is this truck missing something?

Bought the truck used and the exhaust looked like the pics below. It's tough to find stock exhaust pictures to compare what I have to how it's supposed to be so I'm not sure if what I have is correct or not.

I've had the truck for a little bit now and there are no real issues except it always seems to run lean. As such never really had much power so I've replaced or cleaned everything in the intake, vacuum hoses, spark plugs, wires etc and it still runs lean.

From the down pipe I see O2 sensor #1 and that seems right. I don't know what that canister is in the second picture but between the canister and the cat it seems like there should be another O2 sensor and there isn't one. O2 sensor #2 is after the cat in the last pic. Also, in the last picture there is a section of pipe welded in and that isn't stock so what is missing?

Question: Is the exhaust missing something that could cause the truck to run lean? Or anything that looks out of place to you guys that are used to working on these. Thanks for the help!

 

I think there's suppose to be another sensor there

 

Just saw that I posted this is the wrong place. I was looking at all the awesome builds and didn't move back to the main forum lol. Sorry!