TOYOTA fits the H150F five-speed manual transmission to the 78 Series turbo-diesel and petrol models, and the R151F five-speed manual transmission to the normally aspirated diesel models - the main difference being gear ratios. The H150F is derived from the gearbox fitted to 100 Series LandCruiser wagons that were first released in 1998, as these vehicles share the turbo-diesel engine. Toyota claims it has strengthened the 78 Series transmission to provide optimum durability. Input, intermediate and output shafts have been shot-peened to increase service life and triple-cone synchromesh on the first three gears and single-cone synchromesh on fourth, fifth and reverse to improve shift quality and protect against gear wear. The transmission moves easily through all gears and the shift pattern is positive and evenly spaced. All 78 Series models are part-time four-wheel drive and use a two-stage transfer case to engage the front and rear differentials, which share drive 50/50 when four-wheel drive is selected. A limited-slip differential is standard on all models, with diff locks optional on the front and rear axles - which replaces the LSD where fitted. An automatic transmission is not available on 78 Series models. Gear ratios for the H150F and two-stage transfer case when fitted to the 78 Series turbo-diesel cab chassis are: first - 4.529:1, second - 2.464:1, third - 1.490:1, fourth - 1.000:1, fifth - 0.811:1, reverse - 4.313:1, and Low - 2.488:1, High - 1.000:1.