I couldnt remember if this got cleared up in the competition
The Monocoque-series was a completely new design with one of Jaguars first self-supporting carriages. Compared with its predesessor the new body was shaped essentially more flat, stretched and elegant.
JAGUAR Mk X 3.8 (October 1961 to August 1964) No chrome trim on the sides
Raditor grille not devided
Dashboard top without upholstery
JAGUAR Mk X 4.2 (October 1964 to December 1966) Outside distinguishing to 3.8 Mark X only by type designation on rear bonnet
JAGUAR 420G (October 1966 to June 1970) body (carriage) exactly like Mark X
chrome trim on the sides with integrated small blinker signals
radiator grille with strong vertikal middle bar
dashboard with upholstery on top and integrated central watch
two-tone colour on demand
Can you think of any other differences