early 03 was the low power one with the "leftover" 47RE transmissions. Later 03 models all had the HO engine and 48RE trans. "IF" you have a later build, I wouldn't be too worried about throwing a little more power at it. If it's the early build, then the trans would be a concern of mine. Does it still have the "walker pump" (lift pump) mounted on the fuel filter canister? ...or has it been converted to the in tank pump like so many were. In tank had proven much more reliable than the pump on the canister. In 05 all the trucks from the factory had the pump in the tank fyi. Having towed with a 1500 in my past, you'll love the CTD. Nice to have the power to tow where you want without concern. I'm also like the above guys.... still rolling in my 01 CTD