Hi all. Finally got sick and tired of the cracking coolant ball! I chose to go with a Ford unit from a 2003 Ford Focus. It was an easy swap. Used the factory Ford bypass hose cut down to adapt to the factory Rover hose. Also plugged one extra hose barb on tank. The Dorman part # is 603-216. The Ford tank is made for a 20 PSI system, so had to re-use the Rover cap at 16 PSI. Hope others can use this info.

 

I'm planning on replacing mine soon too I found an Allisport aluminum expansion tank that they make for the D1 and Range Rovers but I don't know how well it will adapt for the D2. Here's the one I'm talking about.

 

Did it, looks wayyyyyyyyy bettttterrrr.