Obsolete NBU version, where to get copies?

Hi,

I've been trying to get a copy of NBU 6.5 installers however after trying to get the copy via http://fileconnect.symantec.com it says the product version I've been trying to download is not available anymore. I have checked it with customer care and they also confirmed it's NO longer available.

How/where else can I have a copy of this version? Any comment, thanks in advance.