Rust comes down to how well cared for too, but yes you are correct older modle dodges do have a few more wheel well issued than ford. That's not the case on newer models though and rust is cheaper to fix than motor and tranny. The Powerstroke is considerably more to maintain and repair, the ford automatic is not as durable as the 08+ dodge tranny and the cummins make more power, lasts far longer and gets considerably better mpg. Most body shops replace the wheel well panels for $300 a side, I know because I had mine done on my 06. 600 every 4 or 5 years is a huge savings compared to what you will pay to maintain and fix the Powerstroke and factor in that the cummins averages 3-5 mpg better than the Powerstroke. At $4 a gallon that adds up fast. I'm not bashing, I like the ford too and have had 3 powerstokes, I switched to dodge because the repairs on the fords are a killer.