I got stuck today going through a mud rut. It was a little deep and the center ridge caught the undercarriage. I noticed that I wasn't getting any power to my driver side wheels as the vehicle was leaning that way. The other side just spun and shot water. Why did this happen? I thought my 04 Disco had posi front and rear when engaged in four low. Do I need to upgrade with different hubs or something? Thanks. Dave

 

abs tc, takes place of locking diffs...
you can still get stuck though....

 

On your 04, if you are in a lock position on the t/case, you will have 1/2 your power to the left front tire and the other 1/2 to the right rear, ETC will kick the power from there to where it thinks you need it.
Rover never installed limited slip, all their diffs are open diffs with no lockers.
Drive it for a year or so to learn how to dive off road then if you really need more traction and are open to spending apx. $3500 then we can talk lockers.