Title says it all.. Trying to Dead Thrall a master vamp.. lol

Yes, though they will likely be sub-bosses/mini-bosses at that level. Try Haemar's Shame.

Bloodlet Throne might have one.

More or less anywhere vampires tend to lair. Master vampires can appear at almost any level but typically a a boss. At your level the vampire bosses will likely be Volkihar Master Vampire's whom are beyond the reach of dead thrall even with the necromage perk. And even a Master Vampire can be upwards of level 42 putting it just out of thrall range unless the necromage perk is taken.

yes, im level 70 and just did a side quest with a master vamp...he's my slave, i mean thrall now

Just risen to Level 46, went into a Vampire Dungeon and faced my first Volkihar Master Vampire.

Lydia and I won.