Discovery 200tdi Front Propshaft

I have recently changed my universal joint on the front propshaft only to find that the discovery replacement part dose not fit! On further investigation i found that the one fitted to my 1989-1990 discovery 200 tdi belonged to a range rover classic or a defender 90. My question is has any other early disco got the same propshaft or do you think that at some time in the discoverys life it has been changed? (most likely)