SolidWorks can probably export its own CAD drawings as 3D PDF documents for viewing and sharing purposes, so it would be the obvious choice for sldprt to pdf conversion. If you do not have access to SolidWorks, you have to rely on some third party CAD software alternatives, or some dedicated 3D model CAD converters.
Open SLDPRT file Open PDF fileA 3D product data optimalization software
3D CAD/CAM tool for product development
An online CAD conversion service
A CAD converter with huge format support
A CAD visualizaton, analyzation and translating system
A commercial online CAD converter
A dedicated CAD converter