Hi DDI,
I sent you a PM with more information. How long is your enclosed trailer? The Hensley installation is somewhat involved. They are also expensive, because they have a patent on the system and can dictate the price. However, they work exceptionally well and you are buying nearly 200lbs of high-quality hitch hardware. (They are heavy!) Basically, you only need a Hensley if the combination of weight plus length is enough to overcome a traditional sway reduction hitch. If the weight isn't too heavy and the length isn't bad, you could use a Equal-i-zer (good) or Reese dual-cam (better). Our trailer is 26' and will be just under 5000lbs, so a Hensley is my only choice to keep things safe.
The difference between a Hensley and the other hitches is that the Hensley projects the pivot point forward to prevent sway in the first place. Basically, it makes the pivot geometry act more like a fifth wheel where the pivot point is at the rear axle, rather than at the hitch ball. Hensleys work especially well on the Liberty because there is so little rear overhang, and the forward projection of the pivot point gives a very good mechanical advantage.
Hitches like the Equal-i-zer and Reese DC reduce sway through the use of friction bars or force-production cams. Sway can get initiated, but the hitches are designed to suppress it from going into oscillation.
One thing I like about the Hensley is that hitching and unhitching is very simple. All the major hitch hardware stays mounted on the trailer tongue; you simply back the tow vehicle up so the stinger goes into a coupler in your receiver. This is nice because you don't need to install/uninstall weight bars, get grease on your clothing, etc. like with a conventional weight distribution hitch.
If you want to learn more about it, here is a link to the manual:
http://www.hensleymfg.com/Documents/Hen ... medres.pdf
Hensley Arrow hitches command a high price on Ebay, so you can always recoup your money if you sell the trailer or upgrade your tow vehicle in the future.
- Chris