Looking through the Legacy of Steel archive a few things popped out:
King Tormax, Statue of Rallos Zek, and Dain are always dropping their heads (off applicable) as well as 3-4 other items from their loot table.
On P99, every kill we have had live or beta, we have only seen 2 loot. Can other guilds weigh in here with their beta/live kill experience so we have a bit more data?
I'm guessing 3 is possible, but I do not believe 2 is classic. It should be a minimum of 3 drops maximum of 5.
http://www.legacyofsteel.net/Archives/Post/2001-07-16
That's a 5 loot Tormax for example.
I believe this is the case for most West/North ToV dragons as well. We were only seeing 2 loots per kill and I think 3 should be the minimum number you see as per classic. Same goes for Velketor.