There are really three choices I know of. The one 1Jaguar1 mentioned is probably the JTIS CD. It is OK for the XJ6, but is sometimes hard to find specific things with the search function. Another choice id the original shop manual pdfs from Jaguar Heritage Trust. more complete but again, cumbersome to search at times. I prefer the Alldata.com subscription. I have all three and generally go to the Alldata site first. Its easy to locate info, but it seems like it is not quite as complete as the other manuals. It does, however, have the technical service bulletins. All three include DTCs and schematics. A good manual, a code reader, and a pretty good mechanics tool set is about all you need for MOST things that will come up on your X300. Oh yea, its also good to have a spare Jag to drive while you work on the other one so you are not in a hurry!