A common complaint about the 4.5L V8 turbo diesel 70 series Landcruiser is the high engine rev speed when at highway cruising speeds.
Typically at 100km/h the engine will be revving at around 2400rpm.

This can cause loud engine noise, high fluid temperatures, poor fuel economy and excessive engine wear. Combined these issues can significantly decrease engine life for those vehicles spending a lot of time at highway speeds.

The Transmission Ratios upgrade eases this strain on the engine and prolongs engine life.