I looked for a while and couldn't turn up anything specific to Land Rovers, however, I did find a fair amount of similar parts for other trucks. I "believe" you would need to get a different type of thermostat and use the various parts to build your own. The best results I found were from JEGs key words "thermostat housing"

 

That's the one I need

 

Hell, that's a very nicely made and fancy stat housing LR03NJ, firstly ensure you can buy a regular supply of stats for it though. That's almost an engineering masterpiece.

Would you believe I still have my original stat in my D2, never been or needed to be changed.