Yeah, you have the exact year for it to be a bad one. At least you got 8 years out of it.
HMMWVs have Torsens--3 I think, though there is a center-lock on the t-case to bypass the middle one. They work well in those because the slipping wheel is a 37" mud terrain with a Humm-vee sitting on it. It doesn't make much sense in a little pickup that weighs maybe 1,400 on the rear axle. With the Torsen, there is about 2.5x the torque sent to the wheel that isn't slipping compared to the one that is slipping. SO you have 700# of tire sitting on a patch of ice and able to deliver 15# of torque--the tire on dry pavement can push with 40# of torque. With a real locker, the tire on the dry part can push with 500#, or whatever the friction coefficient is of cold rubber on dry pavement. Pick up a tire with a Torsen and zero x2.5 is still zero. WIth a 4x4 it's no big deal because you have the other end still on the ground. But offroad, it's kind of nice having both ends contributing.
So when you replace that axle, maybe get a standard carrier and a LockRight or get a Detroit No-SPin which comes with the carrier.