This might take a while, but I know I was looking for this when I started, so here goes. I split this into sections to save a little space, let me know if the layout is too confusing. I also didnt include TT drops since farming there for mods would be a terrible idea, imo, and it offers nothing you cant find elsewhere, easier.
General Stamina Mods:
Authority
V - 20 Stamina, 50 Defense - Dorlos (MA), Uguda (Cyclops), Epic 2.0 (Level 36 required to complete)
VI - 35 Stamina, 75 Defense - Iron Rune Warrior (Kalin)
Rigor
V - 20 Stamina, 50 Magic Def - Cursed Iron Golem (MA), Boddosh (Cyclops), Dark Glory Belt (BoE from Mummified in DDC)
VI - 35 Stamina, 75 Magic Defense - Unknown location, presumed to scale the same as Authority.
Endurance
V - 20 Stamina, 50 HP - Dorlos, Aukuda (MA), Locked VII Chests (WW event), Negotiator (Cyclops)
VI - 35 Stamina, 75 HP - Unknown.
General Melee Mods:
Oppresion
V - 20 Stamina, 50 PAtk - Uguda (Cyclops), Boddosh (Cyclops)
VI - 35 Stamina, 75 PAtk - Unknown.
Cougar
V - 15 Str, 15 Dex - Dorlos (MA), GMO (Cyclops), Kula Nail (50 Ice Dwarf Chests)
VI - 20 Str, 20 Dex - Unknown, scaled stats to match Savage.
Savage
V - 15 Str, 15 Sta - Aukuda (MA), Uguda (Cyclops)
VI - 20 Str, 20 Sta - Locatha (Kalin)
VII - 30 Str, 30 Sta - Worr (Minos) (Extremely rare)
Force
V - 15 Sta, 15 Dex - GMO (Cyclops), Kula Nail (50 Ice Dwarf Chests)
VI - 20 Sta, 20 Dex - Unknown
Barbarian
V - 20 Str, 50 PAtk - Aukuda (MA), Negotator (Clops), Lynn (Minos), Thynos (50 Dwarf)
VI - 30 Str, 75 PAtk - Regin (Kalin), Worr (Minos)
Hammer
V - 20 Str, 50 HP - Kula Nail (50 Ice Dwarf Chests)
VI - 30 Str, 75 HP - Unknown
Fang
V - 20 Dex, 50 PAtk - Boddosh (Clops), Any of the Eye/Meat bosses, Epic 2.0 Quest line
VI - 30 Dex, 75 PAtk - Worr (Minos)
Keen
V - 50 PAtk, 50 PDef - Ant Kings, Malatinas, Kula Nail (50 Ice Dwarf Chests)
VI - 75 PAtk, 75 PDef - Ant Queen
Observance
V - 20 Dex, 50 HP - Kula Nail (50 Ice Dwarf Chest), Negotiator (Cyclops)
VI - 30 Dex, 75 HP - Unknown
Paladin
V - 20 Str, 50 MDef - Uguda (Cyclops)
VI - 30 Str, 75 MDef - Unknown
Defender
V - 20 Str, 50 PDef - GMO (Cyclops)
VI - 30 Str, 75 PDef - Unknown
Reflex
V - 20 Dex, 50 PDef - Cyclops Leather boots, boss unknown.
VI - 30 Dex, 75 Pdef - Unknown
Agility
V - 20 Dex, 50 MDef - Uguda (Cyclops)
VI - 30 Dex, 75 MDef - Unknown
General Caster Mods
Thunder
V - 20 Stamina, 50 MAtk - Kula Nail (50 Ice Dwarf Chests)
VI - 35 Stamina, 75 MAtk - Unknown.
Illumine
V - 20 Int, 50 MAtk - Razeela (MA), GMO (Cyclops), Kula Nail (50 Ice Dwarf Chests)
VI - 30 Int, 75 MAtk - Regin (Kalin)
Darkness
V - 20 Wis, 50 MAtk - Old Epic 2 reward, Talomos (TT)
VI - 30 Wis, 75 MAtk - Unknown.
Mind
V - 20 Int, 50 MDef - Dorlos (MA)
VI - 30 Int, 75 MDef - Ensia (Kalin)
Elder
V - 15 Int, 15 Sta - Kula Nail (50 Ice Dwarf chests)
VI - 20 Int, 20 Sta - Unknown
Genius
V - 15 Int, 15 Wis - Negotiator (Cyclops)
VI - 20 Int, 20 Wis - Goddess (Kalin)
Mystic
V - 20 Wis, 50 MDef - OMG (Cyclops)
VI - 30 Wis, 75 MDef - Locatha (Kalin)
Warlock
V - 50 MAtk, 50 MDef - Dorlos (MA), GOM (Cyclops)
VI - 75 MAtk, 75 MDef - Locatha (Kalin)
Soul
V - 20 Wis, 50 Def - Aukuda (MA)
VI - 30 Wis, 75 Def - Ensia (Kalin)
Shield
V - 20 Int, 50 Def - Kula Nail (50 Ice Dwarf Chests)
VI - 30 Int, 75 Def - Unknown
Sage
V - 20 Wis, 50 MP - GMO (Cyclops)
VI - 30 Wis, 75 MP - Unknown
Everything Else:
Blood
V - 50 PAtk, 50 MAtk - Mole King (50 Ice Dwarf)
VI - Unknown.
Rage
V - 20 Str, 50 MAtk - The Ice Thing in Ice dwarf iirc.
VI - Unknown.
Precision
V - 15 Wis, 15 Dex - Unknown.
VI - 20 Wis, 20 Dex - Worr (Minos)
Speed
V - 20 Dex, 50 MP - All over MA.
VI - Unknown.
Fox
V - 15 Dex, 15 Int - All over MA.
VI - Unknown.
Crystal
V - 50 PDef, 50 MP - All over MA.
VI - Unknown.
Savant
V - 50 MP, 50 Mdef - All over MA.
VI - Unknown.