Nope, they didn't make a Mark 11/XI Jag.
The big Mark line used Roman numerals and stopped at the Mark X, which in one variation would become the Daimler DS420 limousine but in all others was replaced by the XJ Series I.
The smaller Jags didn't ever use the Roman numeral system - they went with Arabic numbers. The progression there was the Mark/Mk 1, Mark/Mk 2, S-Type, 420. This line was also replaced by the XJ Series I.
Unfortunately, if you're talking about the Mk2, it's out of my area of expertise. I'm an XJ guy and I really concentrate on the cars with independent rear suspension as many other things changed when the IRS was introduced. The Mk2 was never so fitted. Other than the fact that you need to get a Lumenition or other modern ignition system right away, I don't really have that much worthwhile to contribute. Have you tried over at jaguarforums.com?
