And what was the MY of the changeover? Again, trying to find out whether my '00 is in the clear … 
engine SN 0108130000
It should be in the clear, but you can call Jaguar and give them your VIN # and they will let you know. I am pretty sure the warranty period is over.
ENGINE NUMBER (not VIN) is the determining factor.
engine SN 0108130000 means 2001, August, 13th, MIDNIGHT.
The engine is ALWAYS built before the car!!!
The engine can sit for days, weeks, months before it is installed at the assembly line.
VIN means NOTHING because there is likely no absolute order on engine assys being installed or people swapping engines after the car is sold.
So then likely that means the upgraded engines were installed in only the 2002 and/or 2003 MYs? (and, incidentally, about the same time as the timing chain tensioner upgrade) 
Every source I ever read said that the switch from Nikasil engine bores to iron liners happened in August 2000.
I thought that my 2000 XJR had them, but if not, then it’s evidence that Nikasil was not an automatic death sentence in the USA. I bought it in 2001 with 8000 miles on it and drove it for 15 years and 80,000+ more miles - no loss of engine compression or power.
Basically, if sulphuric fuel didn’t kill the engine by 2007, then it’s no longer an issue (at least in North America and Europe) since high sulfur fuels were banned by then.
The tensioners were updated at least twice. The “ultimate” fix didn’t come until 2004-2005 when they finally abandoned their fetish for plastic and made the tensioners out of metal. All 4.2 V8’s had the metal tensioners. Any tensioner update for a 4.0 AJ-V8 should be a metal one.
Dave
