Saw a beautiful blue 1991 XJ6 4.0, 84000 miles. Very clean I will try and post some pics. Any experiences with the car I should be aware of? Saw one fault 37 doesn’t raise a lot of suspicions.

Almost too clean

 

Looks lovely, but you've posted it in the wrong forum. Its an XJ of the XJ40 series 1986-1994 with the AJ6 all-alloy engine. These cars were a total breakaway from the previous XJs, with virtually no common parts, although the lower ever-lasting front ball joints do retrofit, as I put some on my 1980 XJ6

 

Sorry, I guess I don’t have enough experience with Jaguar to understand all the differences. Is is still in the classic realm?

 

Got a quick less on the XJ series and the AJ6 motor on Wikipedia. Very interesting history. 91 Sovereign looks a good bet.
Thanks