Jarulf's Item Locator?

[Kartoffelsalat]

At D2Data.net they list the chance of drop for each Treasure class by monster. I don't know if this is imuables or just magick or what, but it seems useful:

d2Data

I hope that helps in your search somewhat.

Just from experience, I seem to remember getting ancient axes a lot in acts III and IV, NM. Or maybe I'm just remembering incorrectly. Either way, good luck.