If these were 2 newer trucks like 04's I would vote for the dodge. The cummins is a great engine in and the tranny is much stronger in these years, BUT since we are talking 2001's The tranny's in the dodge is horrible, and I think the 7.3 is the best engine ever made. Not saying the cummins 12 and 24 valves arn't good, but lift and injector pumps have always been a problem.
I'm sure you will get the buy the dodge on TDR, but they are closed minded and remind me of Honda rice burner drivers
You will be happy with either truck, the 2 of them are in the best years these trucks have ever been manufactured. Dollor for dollor with maintance and smaller problems the dodge WILL incure the cost will be more to run the dodge to 600K miles than the ford