are the differentials exchangable with any other years of the same model

Only thing I can recommend is cross-referencing that part on a parts store website and see if the part numbers match.

I suggest that you post this question on a Jag forum. I found several references to this issue with a simple internet search.

That's kind of what I thought this was. A place to post questions. But that's a good idea to check out other sites besides this one. Thanks for the responses.