The rear wiper motor fitted to 300Tdi Discovery 1's (from VIN MAxxxxxx onwards) is AMR3872 - which is no longer available and has been superceded by DLB101640 - which is the same rear wiper motor fitted to all Discovery II's
I believe that some 200Tdi era rear wiper motors will also physically fit a Discovery II, but the loom connectors are different and have to be changed to suit.