A pair of ancient dwarven war constructs with neat designs and... not-so-neat RHD amounts. Let's have a look.
The Behemoth is the bigger of the two, with Huge size, CR 15, and a disappointing 29 RHD. Although its mixture of defenses (energy resistance, DR, SR) and offenses (four slams, 37 strength, Dazing Blow) is nice, it suffers from its huge pile of racial hit dice, lack of intelligence, and general one-sidedness. -0 LA.
Way more viable than the behemoth, mostly on account of having only half as many RHD. It's kind of interesting actually, with some very nasty natural blade attacks, respectable stats, the ability to squeeze into Medium spaces without penalty, and good defenses.
Also worth mentioning is its Enhanced Mobility ability, which should really have been a part of tons of classes and prestige classes. Using it, the eviscerator can move a short distance (15 ft.) in a round and still get to make a full attack.
In spite of this, I think -0 LA is still in order here, simply because losing 3/4ths of your build to construct HD has never been good. I can see a slight argument for +0, I guess.