FIRST thank you for responding. I almost thought this would not get any response.

Quote Originally Posted by StevenC21 View Post
This is wrong. From the vampire template:

"Size and Type: The creature’s type changes to undead (augmented humanoid or monstrous humanoid)".

Note that the subtype also changes. Not "is added", changes. Thus it loses living construct traits.
Yes. Type becomes undead(augmented humanoid) however, other templates that change type like that do not cause you to lose other subtypes. Shapechanger, incarnum, psionic, alignment subtypes, dragonblood, human subtype.

For this reason I believe the warforged would retain the living construct subtype. As other templates and example creatures do not lose their subtypes. So a warforged vampire would be an Undead (augmented humanoid, living construct)

Quote Originally Posted by StevenC21 View Post
In addition, from the SRD, on Subtypes:

"A creature with the augmented subtype usually has the traits of its current type, but the features of its original type."

The Warforged living construct traits are, well, traits. So they are lost upon applying vampirism, if you somehow could.
This is true, but subtype traits are in edition to the traits of your regular type. So the aforementioned type block would have both undead traits and living construct traits.

Quote Originally Posted by StevenC21 View Post
Very neat idea, flawed execution. Still, definitely some hope here. Keep looking for interesting rules interactions, I'm sure you'll find some real good stuff.
The execution may be flawed if con is not retained. But i did mention it could be argued. However. The stacked redundancy of vampire with juggernaut still produces a staggeringly powerful entity with a near comprehensive list of immunities. On the particular character, his pugilist levels also grant him the ability that he only accrues non-lethal damage. Which stacks nicely with immunity to non-lethal. Rendering him immune not only to raw damage, but also the vast majority of save or lose effects.

All in all I think either interpretation of how they interact produces a spectacularly powerful tank build.