My fear is that I would not be able to scale down the parts of the 3d model. but I was able to scale down the parts to a working size without any issues, purchasing the items through PayPal was quick and easy, If you need a file and it is on sale, go for it. models are well done!
The biggest fear was that the model is not very detailed and far from the real crane. But when I open the model using an AutoCAD I found that the model was very very detailed even I can directly use it for an FEM simulation in other commercial software. 3D Models World could help you a lot in your projects.