The UnityPackage contains a Metallic map with Roughness map stored in its Alpha channel. It also includes a basic hinge rig set up in its components (the top part will turn when collided with).
The Source Normal map has had its Green channel inverted and additionally the roughness map stored in its alpha channel. Including a perfect collision mesh for the model. The model is also of course scaled up to meet source engine scaling.
Normal map was baked from a Hi-Poly model onto a triangulated Low-Poly model. Because of that the model had to be triangulated in the .Blend but can be turned back into Quads simply by pressing ALT + J in edit mode with mesh selected. (quality of topology retained)