What IS the record, then?
Well, I just checked and the “John McCain, you treasonous bastard...” thread is nowhere near that. Only 1367 posts. :)
The never dying ZOT threads
http://www.freerepublic.com/focus/f-backroom/1306051/posts
http://www.freerepublic.com/focus/f-backroom/1306051/posts?page=36013#36013
The Hobbit Hole threads are also records for replies.
http://www.freerepublic.com/focus/f-chat/807952/posts
Try the above for one but I think there are others with as many.