Uh,
@Navigator Mike, you might check
Wikipedia.
I had three Jags, pretty much up on their history through '74.
The V-12 required so many changes to the car, they actually dropped the 'XK' moniker officially (though everyone still calls them that), as I had one of the first Series 3 E-Type V-12 imported - that was 1971.
The first E-Jags in the U.S. were 3.8 litre straight sixes.
In '68 this was increased to 4.2 litres.
Fantastic cars for a teen in the sixties, and I *know* what it is like is some small respect to be a pretty girl, because when I drove those cars, they turned heads.
Speaking of sacrilege, I wanted a manual transmission, so at the time, the engines had a terrible reputation - having dissimilar metals in the engine caused no end of problems - and Lucas electrics don't get me started - so there was a market for guys who would remove the V-12 and install a Chevy 350 V-8, but they had a terrible time finding the correct matching parts. So when I called a guy down in Texas who did that work, he sent me an engine/trans combo in return for the bell housing from my automatic transmission.
I did a hatchet job on the drive shaft tunnel to make the opening for gear shift lever, and that was in 1986. So the car ran -- maintenance was easy: 12 quarts of oil, 12 spark plugs, synch four carburettors -- until I sold it "just in time" in early 2008 before the crash.