I have a 1995 XJ6 that I am very fond of already, I've found a very nice XJ8 (2000) with less than 50,000 miles cheep. it has an issue, probably major, but that's why I am asking a question. the gearbox fault light is on , it is slow to pick up speed but is drivable . question is should I run like a deer or is a reasonable repair possible.

 

Hi
Before to repair the gear box is important to clean all electrical connection to all computers. Some time you will find that a bad connection is responsable for many prolems.
I have a 2000 XJR it has Mercedes not a ZF gear box but before to clean most of the electrical connection some times on my dash bord appear the message gearbox fault and restricted performance. After the cleaning no more message and the car runs very well. At 50000 miles a gearbox to be bad is very unusual.
Best regards

 

The ZF transmission is subject to A drum failure, and while not common at 50 K mi. it is not a surprise. If you are unable to remove and rebuild it plan on spending $2500 or more.