2016 Ram 1500 quad stock exhaust question

[JimGregory]

I was just under my new to me truck installing nerf bars. I noticed a long straight run of exhaust tube that appeared to be aluminum. I was suspended by rusty steel brackets. I could see pitted corrosion on the aluminum from the whole dissimilar metals thing.
Did I really see that? Doesn't seem like that aluminum tube is going to last very long.

 

[Hemi450hp]

The factory exhaust tubing is 409 stainless. It is going to show surface rust over time though.

 

[JimGregory]

It looks like aluminum a lot. All the bits before and after that straight tube look like stainless. I will add a pic soon as I get a chance.
I must be wrong though. Sure looks like it would be a point of failure but apparently it isn't.
Plus it would just be a damn stupid thing to do.