Aluminum adapter for adapting pre-1975 (drum rear brake) final drive boxes to post-1975 (disc rear brake) swingarms on Tonti frame big twins. This adapter will allow you to install an early final drive box from a Guzzi with a drum rear brake (most 1967-1975) onto the swingarm of a bike with a rear disc brake (normally 1976 - and later Tonti big twins), while maintaining correct axle alignment. This device allow use of drive boxes containing various early gear ratios on the disc brake models without transfering the actual gear sets into the later drive boxes. This is a great item to enable multiple gearing options, as well as to enable a final drive box swap that would otherwise be impossible.
Note: this adapter is designed for use with 2 of the original 12352900 gaskets which are sold separately.