We own an older Dodge Diesel that we bought new and now has 142,000 miles. It is supposed to be one of the "better" years. It has done a fine job carrying our pop up camper and towing our horse trailer. However last year it needed a new turbo and the price was close to $5000.
From what I have read the new V-8's tow nearly as well as the older diesels. The new diesels are tow BEASTS!! However they cost more, do not produce the MPG of the older diesels, are more complicated, and perhaps they are more prone to expensive repairs.
When we replace our diesel it will more than likely be with a new V-8.