I know this isn't the most exciting post in the world, but it may be useful to some nonetheless. When we bought our trailer it came with a strange looking inverted king pin hitch(strange to us). We had seen fifth wheels, but this is a fifth wheel turned upside down. Unfortunately we had to do what we could do to get the trailer home so we ended up cutting a huge hole in the bed of our brand new truck. The hitch has actually worked well enough for many years, but eventually the lack of sideways movement etc. ended up taking its toll. It has to give somewhere, and it gave in bending the hitch cross member in the truck as well as wearing out the pivots of the hitch on the trailer. We looked at allot of different options including a normal fifth wheel set-up but finally decided on the goose neck hitch. From what I was able to dig up, the design of the fifth wheel does allow you to potentially pull more weight because the weight is over a wider area and the pin is not supporting the weight downward, only the weight of the trailer as it is pulled forward. This is the reason you see big rigs with this type of design. However, since we are only hauling approximately 20,000 pounds and most goose neck hitches are rated at 30,000 we felt pretty comfortable with the goose. The advantages of the goose are an obviously simpler design with less parts, the latch is only for safety and does not hold the weight of the trailer as with a king pin so the latch is not what is holding the trailer, you don't have to get in the bed of the truck to latch or unlatch the trailer(once we get the cable hooked up), but the single biggest advantage in my mind is the fact that you don't have to be lined up on level ground to attach the trailer! This was a huge frustration for us if we unhooked out in the boonies where the ground was less than perfect, then tried to hook back up. With the goose, you can unhook and hook up at most any angle. Also a huge plus that goes along with the simple design and less parts is that it has a firmer feel to it(so far). The goose will also allow more movement, but we will have to pay attention because it will allow the trailer to bend far enough sideways to hit the bed of the truck where the old hitch would not.
Here are a few pics from the install. You can see that we had to cut through the THICK 4" pipe at a 45 degree angle so it would set into the pipe on the trailer correctly, then we just welded it on. The hardest part was cutting all the old crap off, both on the trailer and on the truck, also fabricating the plate to cover the hole in the bed was a little tricky, but I'm happy now. It looks good. If you don't already have a huge hole in your truck(most won't!) you only need a 3" round hole for the ball to stick up through. The ball turns over and out of the way very easily.
