The stand alone version was discontinued when Design Extender was released.
If you wish to use the Stand Alone version of Site Import, you will need to continue using it in the older version of Dreamweaver.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.