TV for 400 Jeep Grand Cherokee.

I've done HOURS of research on this. From what I understand, the 3.6L V6, with the tow package will tow 6200 lbs. What's so confusing is the engines vary year to year. You'll need to look up the specific year for the TRIM you are looking at. Do not listen to the car dealers, as they know next to nothing about towing. 

Yes, I have the Jeep V6 worth the 8-sped auto trans, on the Gladiator and it mote than handles the Tab 400.  It is more about haw much torque, than speed, when towing.
cheers