Looking to purchase a used 2015 wrangler unlimited, having some concerns with the rusting on the drive shaft and undercarriage.
should I be concerned with the amount of rusting? Any advice is appreciated.

 

That undercarriage is considerably more rusted than my 2014 is now, or my 2012 was before I sold it last fall, and I'm in the salt belt of NJ. Drive shafts always rust, so I wouldn't be concerned about that. But the rest of the parts don't look good to me.

 

That does look rusty. Probably not oil sprayed or under coated. You might be able to slow it down with a spray such as Krown, I had my Used 2011 sprayed and it Made a difference. They also have a new product they call salt eliminator. I just purchased a JKU that has some rust like yours and once I’ve done the safety it will get sprayed. Will try to get before and after pix. I would be interested in how bad it looks under the hood.

The muffler is something that I did notice. If you are planning on swapping to a different one then it should be fine but almost looks like a leak.