Power is never a concern, usually the question is fuel mileage:

For fuel mileage if you can find a First Gen with 3.08's is the best.
Second choice is 3.54's and those are available all the way to '02.

The 02's and prior are the most reliable engine-wise, but there are issues with the 5 speed reliability.

Despite the complete BS that gets printed on here, it's common knowledge in the Dodge Diesel community that the 03's and up common rails are reliability nightmares and fuel hogs. 3.73 gears are the reason fuel mileage took a dump. The common rail problems and schitt mileage are openly admitted from Cummins (I deal with them a lot). It sounds like Dodge addressed all the complaining did something about the fuel mileage and went back to a 3.42 diff.

What are you planning to use it for?