That's a good question, whether or not to change the diff. I only did mine after our first big tow because we burned up the oem dino oil and had to take it to the dealer to inspect. After changing to synthetic and putting the alum finned cover on, I've had no worries. But with a first tow, you may have some initial wearing that might call for a fluid change. See if any experts chime in.
Glad you had a good time. Towing with the Titan is a treat because it pulls so easily and it handles so well. Hope this turns into a regular family outing for you. We've been doing it since summer of 04, right after I got the beast, and it's by far my favorite way to vacation.
Enjoy!
