Dear @Mohit_Gupta
Thank you for your post.
Older versions of PDFCreator Free can be found here: http://download.pdfforge.org/download/pdfcreator/list
Unfortunately, we do not offer to download version 1.7.3 anymore. We would like to know more about your reasons why you would prefer to use version 1.7.3. It would rather difficult for us to support old versions of PDFCreator including how to correctly license the software for your customers.
Kind regards
Sascha