The more I read the more lost I am. I have an 03 Disco and one of my future goals is to add true four wheel drive to it with locking differentials. If I go with an ARB kit would that include all I need, minus the AC, do I have to replace both diffs and the transfer case, just the transfer case, just the front and rear diffs....... I have tried to educate myself on this but I just get more confused. The answers I get stop just short of the info I need

 

The transfer case does most of the locking. There are parts inside the transfer case called differentials, they are of course different than the front and rear axle "pumpkins".

Some years of D2 had the fitting on the transfer case, but did not have the shift lever, and there are kits for those. However, I think your year needs extra parts. A pile of parts.

see Expeditions West: Land Rover Discovery II CDL

and

2003CDLInstall - LAND ROVER CLUB V.I.

 

but if you want all 4 wheels to be driven, you need a locker in the transfer case, and one in each of the axles. I'd start with the transfer case first. (and I will... when I get time.)

 

I agree with Jafir. I true locked up truck, 25% power to each of the 4 tires will require converting/modifing your t/case to a CDL case then adding a rear and front locker to each diff.
If you want to explore your options, send me your number and I'll be glad to walk you thru all the lockers and what sort of money you are looking at.

 

Yep, the changes to the case get you to where a stock earlier or later unit is with CDL. Our other Jeep friends have had that low-lock option for awhile, not sure why Rover thought we couldn't handle all those options.

 

Convert your center diff to a locking one then drive it where you'll normally be off-roading to see if you really need locking axle diffs. Even without traction control (i.e. D1's, Defenders, etc.) and a CDL Rovers are very capable off-road.
I think for the majority of the average owners a winch before axle lockers will be money better spent.
A winch may not have the coolness factor of axle lockers, but it will get you out of more bad situations than lockers will.

 

And that is from a guy in a place with hills made out of red clay mud....

 

I appreciate all the feedback. The way one site would call the Cdl the cdl and others caked it a transfer case had me refused. That and it only made.sense that you would need 3 different pieces to lock it 100%. At least a cdl and either locking diffs or change the axles altogether.