SUV 4wd technical question

[Swordman]

Hey folks, I'm hoping someone can answer these questions.

In an SUV with switchable 4wd (like a Nissan X trail), am I right in thinking they have a locking centre diff? So, if one wheel loses traction, only that axle spins away the power and the other axle provides the traction?

The Suzuki Jimny has vacuum operated 4wd; does that operate the same way? And has anyone got experience with the traction control of the new Jimnys; are they as good as lockers?

[Swordman]

Thanks for the 300bhp/ton! I've now bought a Jimny and I've also bought some maxtrax boards for desert dune bashing - should be fun!