Land Rover Repair: Defender differential and third differential, limited slip differentials, rear axles

Question
The Land Rover is a legend indeed.
I want to know whether the Defender front and rear axles are fitted with LSD as standard. If so, how does LSD work ?
What is third differential?

Many thanks

Answer
Land Rovers Defenders do not have limited slip differentials as standard.  Newer models have optional electronic traction control.  The transfer case contrails a lockable center differential, which, when locked, provides equal drive to the front and rear axles in situations where one end of the truck may have lost traction