Humming noise

Hello, I have a 2000 model Cherokee with a 6.5 lift. I installed a Hack n tap to get rid of the driveline vibs at highway speeds and it worked, but now when I pull a trailer I get a humming noise. I checked everything on it and everything seems to be tight, no slack at all. Does anybody have an idea on what it could be?:huh:

Your driveshaft angles change with the added weight,plus you may not have got rid of "all" the vibes by using a H-n-T. What T-case do you have?