I used a 14,000 pound capacity EAZ-Lift weight distribution hitch on both my TTs, one of which was a North Trail, and pulled them with an F150 and F250 respectively. Never had a problem at all, but they have to be adjusted correctly to work right. Apparently, not all dealer know the correct adjustments (height relationship of hitch ball with the trailer ball cup). I am not sure what E4 is as I thought it just meant 4 point weight distribution. I would read the specs for whatever hitch they are installing and make sure that it is correctly adjusted before you hook up to it.