I towed across country ONCE with my 71. Last time I'll ever do that again. It was a tandem axle trailer with brakes, loaded with a medium sized sedan. Bronco had plenty of power, but when I was headed down a long downhill run on an interstate in west virginia, things went downhill fast (sorry for the pun)

Basically at about 60 mph the trailer must have shifted on the axles and became a little light on the tounge. At that point the rig proceded to pick up the *** end of my bronco and bounce it from one side to the other. the rocking and slamming back and forth proceded to get worse and I thought for sure I was going to become a statistic. Only thing I could do was step on the gas to get the rig to straighten out. It was about 80MPH before it came under control, and I was still going down hill. Luckily the grade change to a gradual up hill and I let the whole thing ease off. That was after about 600 Miles of towing that it did that and it didn't do it again for the rest of the trip.