I recently purchased a Mark III 1966 which was originally an Automatic and later converted to manual. Possibly the complete frame including engine and manual gearbox has been replaced. I wanted to check the engine number and discovered it has a "C" suffix instead of an "A", as described in the repair manual. Does anybody know what this "C" suffix is referred to ? Does it indicate the Mark II "C" models with Weslake head of 1964-1965, as described by James Taylor in the Rover P5 / P5B book ?