I have the Ram 20k slider hitch which is made by Curt. I like the hitch, it is easy to use and works very well. It is also easy to slide back if necessary.
The downside to it is it is heavy as he!! and it is quite difficult to remove from the truck. I have to take it out in 3 pieces (head, slider rails, and picture frame adapter) because it is too heavy to remove as one. I actually leave it in the truck now because it is too much of a hassle to remove.
Overall it is pretty good but the only reason I have it is because I had it thrown in on the deal on my truck. If I was purchasing a hitch I would likely go with the B&W 3600.