I read the rules before posting this. Don't take me wrong on this one I love KAT and is the best torrenting site i've ever participated the community is AWESOME! But lets get real wheen it comes to documentaries especially those before 2008 it is really hard to find those. So I am just asking your opinion fellow KAT users =)

Your best bet would be a private torrent site;

thebox.bz is quite an easy site to get into and has a category for documentaries (which contains over 13,000 torrents)

I have to recommend checking out eztv if you like documentaries of the National Geographic or BBC varieties. The MV Group is a good source for docs, and eztv has a number of them listed here:
MV Group on EZTV
I started using torrents with TV shows from EZTV. Then I learned much more about torrenting after I got into the KAT community, but I still check there first for TV shows just because of the layout/ease of use when looking for tv shows.

http://kat.ph/user/MVGroup/

He's right EZTV does always have alot of fresh Docos on it, but you said your after old ones .... and bunabees also right, mv-group is a great source.
Dont get me wrong though i only go to EZTV to see whats freshly up, I always come back to KAT to get the torrents. Gotta help with the seeds ya kno

Did you wake up this morning and realize there's a crack in the bermuda triangle or something.. OMG!..

uTorrent still has mininova as one of the default search providers

KAT ;P

yes, our home is the only place I recommend, since it's the only site i use. ^^"

doesnt get any better than kat