O2 sensor question

[Troy's QC SRT]

I'm thinking about replacing my 02 sensors...... Before you ask why....I just want to.

Which 02 sensors are for what?

1. The 2 front sensors in the headers
2. The 2 behind those in the mid pipe
3. How much are they from the dealer and what are the correct mopar part #'s because i'm pretty sure there different.

 

[wesalbert]

How did you break it?

 

[Troy's QC SRT]

How did you break it?

Lol their not broken visually, just trying to weed out some factors and I don't think it will hurt to replace them with known good correct parts.....I just want to know which sensors are for what to help me think.....