Hopefully this isn't a repeat; I didn't find anything specifically on adding a Land Rover OEM compass mirror to a '99 DII.

My mirror had the broken seal and was filled halfway with fluid, so I was in the market for a new one. I went to the junkyard today and happened to find a compass mirror from a wrecked DII that looks brand new, got it for $35. I found a thread on a Range Rover forum about them adding a DII mirror, and since they have the same black, grey, and white wires as the non compass mirror DIIs I figured I'd give it a shot. Here's the thread

Rear View Mirrors

It took about five minutes to wire up, and the mirror clips on perfectly, now I have a compass mirror in my '99 DII.

 

Cool. My 99 has the same mirror problem you had. I'm gonna start looking for one of these! Thanks!!!

 

I'm only bringing this back to life, so I can find the thread again and the link to the wiring write-up.

Hopefully this will work on my truck too.