..or is it the other way around?

If you've selected to "Show all threads" in forums, you'll see that "all" means 1000 days (see the actual url).

If I'm not mistaken, this vBulletin forum was started 9th Feb 2002.

1000 days from that will be due on 5th Nov 2004.

While after that I could still read older posts by editing the url manually, will/should this be changed?

I hope this site will still exist by then :)

Actually it was started on 8th of feb :D

But still you have a good point.
Earlier we've changed software at an interval that meant we never had a problem with this, but no idea what'll happen this time.

Julio or Per?

Nothing bad will happen, you just won't see threads older than 1000 days after that.

Very interesting find Mictlantecuhtli. Looks like we will just have to manually find them soon.

vB3... soon ;)