Is there any rhyme or reason to where or when Set Items drop in Diablo 2?

The title says it all, basically I'm wondering if Set Items are more likely to drop from specific bosses, or are they just as likely to drop anywhere any other rare is likely to drop?

Note: I know bosses have more chances to drop magic items, but I'm more curious if certain sets are supposed to drop from certain bosses or not.

Solution 1:

Monsters have "Monster Levels" and some items only drop if a monster is within a specific Monster Level. I think these are called "Treasure Class" for the items. TC87 is the highest TC (Elite versions of items) and only drop from monsters with MLvl 87/88+. (Not sure of the exact numbers)

When an item drops, the game randomly decides on the quality (damaged, normal, superior), sockets, ethereality, if it will be magical, rare, set or unique. So the best chance of finding a specific unique item is to kill monsters which can drop normal or better quality of the item class and hope for the best. +Magic find items really help here.

Some areas in Hell have monsters where they are mostly MLvl 87+. The Pit in Act I, Diablo's Sanctuary in Act IV, Worldstone Chamber in Act V off the top of my head. So you have a good chance of finding every item in the game in those areas, without the difficulty of fighting Hell Baal. Although Hell Baal still has better chances of dropping the goods.

My favorite is Pindleskin, the unique undead warrior in the garden of Nilathak's (sp?) temple. He is only MLvl 86 so he can't drop every item, but he is super easy to kill and fast enough to access.

Also, you might think that TC87 uniques are the hardest items to find (not counting the high runes [f*ck you, Zod]), but TC3 uniques are (almost) just as hard (e.g. Torch of Iro, Wand). They are too low level to drop frequently in Hell, and the only place they drop frequently is in Act I Normal, but since the monsters are so low level, they don't drop uniques as often.

Solution 2:

There is no drop bias for sets. The only variables are Magic Find and Item Level (and obviously some monsters / bosses have a higher magic item drop rate).