vehicles during 1987, including a continuous run over 24 hours at over . The VM were replaced by Land Rover's own 200Tdi turbocharged diesel engine in 1992. and 300Tdi at the end of 1994. Transmission The Range Rover used permanent four-wheel drive, rather than the switchable rear-wheel/four-wheel drive on Land Rover Series vehicles, and had a lever for switching ratios on the transfer box for off-road use. Originally, the only gearbox available was a four-speed manual unit, until Fairey overdrive became an option after 1977. A three-speed Chrysler TorqueFlite automatic gearbox became an option in October 1982, after years of demands from buyers. This was upgraded to a 4-speed ZF box in 1985, coupled to an LT230 transfer box. The other major transmission upgrade in the Range Rover's lifetime was the switch from the LT95 combined four-speed manual gearbox and transfer box to the LT77 five-speed gearbox and separate LT230 transfer box in 1983. The LT230 was later used on both the Defender and Discovery models, but was replaced on the Range Rover by a Borg Warner chain-driven transfer box incorporating an automatic viscous coupling limited slip differential – earlier transmissions had a manual differential lock (operated by a vacuum servo on the LT95 and mechanically on the LT230). The LT77 had two major design changes: first an upgrade to larger bearings for the layshaft and new ratios around 1988, then a newly designed synchro hub for third and fourth gear and double synchros for first and second. This is also known as the suffix H gearbox or LT77s. Australian assembly Jaguar-Rover-Australia began assembly of the Range Rover from CKD kits at its Enfield plant, in New South Wales, Australia in 1979. Government increases in the tariff on parts led to Australian assembly being discontinued in 1983. Venezuela assembly The Tracto Agro Group, representatives of the Land Rover brand and the Mack truck brand in Venezuela, starting in 1973 and after making investments to prepare the Mack of Venezuela assembly plant, in the city of Las Tejerias, assembled with CKD kits, the Range Rover Classic between 1973 and 1981. North American market Although the Range Rover was designed with the US market in mind, and was planned to be launched in the US in the middle of 1971, with a base price of $5,300, it didn't come to fruition due to the lack of finance, production capacity, and new US