Hi Antonio.
Now I know which sword you've been referring to! That's not a Montagnard dha. That's a contemporary Thai sword that fits loosely into the "Shan" category (although we need to revisit that typology--someday.).
Here is an excellent thread on the old forum that Ian started regarding these particular swords:
http://www.vikingsword.com/ubb/Forum1/HTML/001291.html
The fact that this particular sword is contemporary should not discourage you. It is an historical style, and is my personal favorite (I, too, favor the 1/3 handle, 2/3 blade distribution for my swords, particularly those I cut with).
I have several older examples of this style in my collection, and the custom sword I comissioned from John Lundemo was based on it:
The sword you posted is no longer in my possession (I gifted it to Ian some years ago to assist him in his research of these contemporary Thai swords). However, I'll be happy to provide you with the stats on my Lundemo dha, as well as some other older, but very similar, Shan/Thai swords. In fact, one appears in my avatar.
Best regards,
Andrew