XJ6 (1971-87): Series I 4.2 from engine no. 7L35133, 2.8 from engine no. 7G17029 plus all Series II and Series III models • optional, for conversion to an 123 ignition system: all Jaguar 6-cylinder-models with XK engines, except early XK120 up to 1952 and all cars with 2.4 ltr. engines