Re: "chipping". You can do a lot with your 7.3, and it won't hurt it a bit, but you don't need to for what you're towing. You can however improve your trans performance, and actually keep it cooler by using a programmer to increase line pressure, making shifts quicker (less heat build up), and if desired increase the RPM at which shifts occur. It would also keep the torque converter from unlocking as much. I did this on my 2003 F150, it was a towing tune, and it IMHO helped with trans temps, and longevity. You've got a good truck there, so good luck, and I hope your leak problem is solved.