Here, Made an update:
Current update
Armour: Can use all light
HD: 1d6
Skills: Bluff, Craft, Stealth, Linguistics’, Profession, spell craft, use magic device, Intimidate, knowledge arcane, knowledge religion. 2+Int modifier skill points.
Saves: As per sorcerer
Spells: As shown
BAB; as per sorcerer
Lv1: Charnel Touch, Spells, Negative energy Channeling (As per cleric)
Lv2: Craft wondrous Item
Lv3: Advanced Learning, +1 natural amour, DR2 Nonlethal damage/ Slashing or Bludgeoning.
Lv4: Resist 2 Electricity and cold.
Lv5: Advanced Learning, Fear aura
Lv6: DR2 Nonlethal damage/ Slashing or Bludgeoning.
Lv7: Advanced Learning, Summon Familiar
Lv8: Scabrous Touch 1/day
Lv9: Advanced Learning, +3 natural amour.
Lv10: Enervating Touch
Lv11: Advanced Learning,
Lv12: Scabrous Touch 3/day
Lv13: Advanced Learning,
Lv14: Resist 4 Electricity and cold.
Lv15: Advanced Learning,
Lv16: DR6 Nonlethal damage/ Slashing or Bludgeoning
Lv17: Advanced Learning,
Lv18: Enervating Touch
Lv19: Advanced Learning,
Lv20: Lich transformation(No +2 to ability scores)
Notes: I houseruled for charms to work on intelligent undead.
As a result the dread necromancer is a very defencive caster with armour bonuses and immunities higher than on the sorcerer but in the end is still quite balanced