The power train was completed by a Thornton Powr-Lok limited-slip differential. Stopping power for this heavy car came from power-assisted four-wheel disc brakes, the rear units being mounted inboard alongside the differential. Power-assisted steering was standard, the later 4.2 cars receiving Marles Varamatic Bendix (Adwest) variable ratio steering boxes, designed by an Australian, Arthur Bishop. For the London Motor Show in October 1966 the Mark X was renamed the Jaguar 420G (not to be confused with the smaller Jaguar 420). The 420G was distinct from the Mark X only with the addition of a vertical central bar splitting the grille in two, side indicator repeaters on the front wings, and a chrome strip along the wing and door panels (two tone paint schemes were also available with the chrome strip omitted). Interior changes included perforations in the central sections of the leather seats, padded dashboard sections for safety, moving the clock to a central position, and the introduction of air conditioning as an option. A limousine variant was available on the standard wheelbase; a fixed, one-piece seat back topped with a sliding glass partition replaced the separate chairs of standard cars. Despite running for the same length of time as the Mark X (five years) the 420G sold in less than a third of the numbers. This lack of popularity and the increasing production of the smaller XJ6 resulted in the 420G being run out of production in 1970. In 1968 British Leyland ended production of the Daimler limousine DR450 and the Vanden Plas Princess and chose to replace them by offering a extra-long wheelbase 420G with an eight-seater Hooper "Empress Line"-inspired (but still monocoque) body made by Vanden Plas. Aside from the shape of the rear part of the coachwork there was no link with Daimler cars made before Daimler became a subsidiary. British Leyland's "Daimler DS420" was announced in June 1968. Taller than the 420G the new car was nearly nineteen feet long and six feet six inches wide with "majestic proportions". The rear compartment carried six people in comfort on the rear seats and three fold-away occasional seats. Sir William Lyons pointed out it was less than half the price of any of its competitors. The 420G wheelbase was extended by 21", with the mechanical underpinnings of the car being subtly reconfigured.