Bounty Hunter Archive

Can you loot SEA's from the normal boss marks (single white chevrons) or only the elite boss marks (double gold chevrons)

Also, is there certain payout for npc missions that tends to drop loot like sea's or crystals more often than the others?

100% random. I've looted a descent AA off a silver chevron elite and next mission against same type looted bugs. Double gold bosses are good for dropping multiple items but no guarantee of anything worthwhile.