2003 early build CTD will have a 47RE, later builds with the HO engine will have the 48RE trans... either way, if you are seeing that temp while towing, you've got problems either electrical or mechanical. You didn't state at what speed you were experiencing this. In a "normal" state the only way I could see this trans achieving those temps is if you were climbing somewhere at a slow speed and torque converter lock up could not be achieved. My race trailer weighs in at the 9-10K range and towing down the road lockup achieved will run in the 150 range. This is on my 01, but any CTD with the RE trans I've seen similar results.