Crane with Swinging Load using Configurable Joint

I would like to set up a crane that can move objects around a scene. So far I have been using a Configurable Joint to achieve this and got the swing nailed. However, I would like to adjust the length of the 'rope' from the crane and the load. I have seen a couple of forum posts and have been experimenting with the Linear Limit and Connected Anchor but cannot get the correct behaviour. Is this not possible with a Configurable Joint alone or is there something I'm missing?