This .STL of this truck is too complex to import into SOLIDWORKS directly as anything but a Graphics Body. SOLIDWORKS has a hard coded facet limit for .STL imports (probably due to how long it takes to import long .STL files). There is a workaround to the facet limit using MeshLab to first convert into 3D DXF then import that instead. Like this:
The process takes a lot of time and RAM so make sure you have plenty of both when you start this.