On a 2001 XK8 is it possible to know what generation of timing chain adjusters were used by the VIN #?

 

No.
Engine number only. This will either be stamped adjacent to the thermostat tower or on the block near the motor mount. This thread will show you where to look:
https://www.jaguarforums.com/forum/x...1/#post1934865

Changeover date was reputedly August 13 2001, so engine numbers 010814 0001 and up should have metal secondaries. It is very unlikely that your car will have them unless changed by a PO.

 

so if I located a 2002 MY XK8 with a 02xxxxxxxx engine number it likely has the latest chain tensioners. I have been looking at 2003 MY because of this issue

Randy

 

That would work.

Take a look at the 'Points of Interest' in this Heritage document:
https://www.jaguarheritage.com/files...is_numbers.pdf

You will see that the introduction of MY2002 predates the metal tensioner changeover so cars of that MY early in the production run may not have them. MY2003 onwards is the 4.2L motor, which does.