I was surfing Kijiji and found this 99 with what looks to be an aftermarket Alpine installed in the dash. 1999 Jaguar XJR Leather Sedan | used cars & trucks | City of Toronto | Kijiji

I have seen some people ask if it can be done so here is proof that it can be done. Not sure how it was modified to fit

 

It's a common kit. Basically just a panel in the right shape to fit the gap around a single din unit, which slots right in
https://www.jaguarforums.com/forum/x...y-50635/page4/