The conversion adapts the Ford type 9 gearbox to mate directly to the back of the MGB engine using a custom made, lightweight, cast aluminium bell-housing.

Kits are available to cover all MGB cars - from 4 synchro models with the wider gearbox tunnel to 3 synchro ones with narrow tunnels.

The standard ratios of the Sierra gearbox suit the MGB well, with a 10% higher second gear for better overtaking. The 5th gear ratio is exactly the same as the MGB overdrive ratio. Various alternative gear ratios can be provided including a heavy duty gearset, closer ratios or a standard ratio gearbox with a higher first gear of 2.98:1. The conversion is totally non-intrusive to the MGB. There are no holes to drill, no metal to cut or remove. The car can be returned to standard easily if required.