Oshkosh lockers...
From my memory of working at Oshkosh Truck -- now nearly 10 years ago -- HEMTTs have limited slip rear axles only. PLS trucks (5 axle) have lockers that engage with air switches, but I think only the rear three lock. We did have some cool independent suspension prototype PLS trucks where you could lock all five axles... Those trucks were amazing offroad, and could easily keep up with a tank. I don't remember about LVS... I don't recall unhooking air lines for the axle lockers, so I'm betting they had the same LSD as the HEMTTS, though perhaps in all four axles. This combined with the ability to pivot in the middle allowed it to "wallow" through just about anything. MTVR's can lock all three. Can't wait untill those come up on GovLiq!! Didn't spend much time with HETs, but I'm pretty sure you could lock the rear triple up.
I think having power steering is just about a necessity with lockers, which may be why the're more common on newer MV's and not so common on older ones.
Man I miss Oshkosh Truck!!
C