There's a complete list here;
http://www.uoguide.com/Dawn's_Music_Box
In my experience, "Ambrosia - Common" drops about twice as much as any other gear. In the 550 I collected, "Dungeon - Common" only dropped twice in total, and "Grizzle's Dungeon - Uncommon" only once. I got no Rares at all, despite killing somewhere between 300 - 400 Paragons (I kept the cocoa drops until I filled a chest with them all). "Wanderer - Rare" no longer drops at all, being part of a discontinued quest.
Not including a few I sold or gave away to others, my current sets of Gears are, from the total 40/12/4, as complete as follows;
40/12, 40/12 (sold this one), 40/11, 39/6, 39/4, 39/3, 39/3, 36/3, 33/0, 32/0, 27/0, 23/0, 19/0, 14/0, 13/0
As you can probably see from numbers, there's a certain amount of "streakiness", in particular, the 3 Uncommon gears, "Elf City", "Melisandes Lair", and "Good End Game (U9) are relatively more likely to drop than any other Uncommon. Whether that's a problem with the streaky UO random number generator or not, I don't know... but I bug reported everything I noticed as I thought I had a large enough sample size by now

Hopefully it'll be much easier to fill boxes soon... Also that they brought back the OLD Occlo music!