Depends on what you want to know.
If you're looking for general tech, I gotta go with the Rev - finding XJ-specific tech is what got me in here all those years ago. Go through the archves, and see what you can see (and get ready to buy bigger hats - you'll need them to have room for everything you're going to learn.)
If you have specific questions, try the "search" button above and to the right. There's a lot in here, and you might have to try various terms to get the results you want - but it's probably here.
If that doesn't pan out - ask! Make sure you include all relevant information (like a lot of noobs here don't - then get sore when we ask them what they're working on. It does make a difference...) and we'll do what we can.
I'd estimate at least 300 man-years of XJ-specific experience here, and probably three times that in general mechanics. If you can't find out exactly what you're looking for here, we should at least be able to put you on the right track...
5-90