Currently running 5.6 and would like a two set DVD of that version. However none of the mirrors offer pure DVDs only Torrent versions which involve the possibility of bits being tampered with and things leaving my servers without explicit knowledge and authority.
None of the CD / DVD sellers I have contacted can offer Centos 5.6 DVDs because, they say, they can't get a virgin 5.6 DVD only Torrent.
that argument is a total red herring.
torrents are digitally signed and protected with MD5 checksums on each block, they can't be tampered with as long as you get the original .torrent file from a reliable source.