Help getting Parallels 6 on my OS X 10.7.5

I would like to have Parallels 6 on my MacBook Air. I purchased 5 then upgraded to 6 and my hard drive went out and Apple replaced my hard drive. I have never reinstalled Parallels 6. Now that I want to try it out again, I cannot locate the download for Parallels 6, the only version I can find is 8. Is there any way to get a download for Parallels 6? Are you willing to assist me with my problem? Thanks!