Changes made by Council Directive of 25 July 1978 on the approximation of the laws of the Member States relating to the driver's seat on wheeled agricultural or forestry tractors (78/764/EEC)
EU Directive 1978/764
No changes made by Council Directive of 25 July 1978 on the approximation of the laws of the Member States relating to the driver's seat on wheeled agricultural or forestry tractors (78/764/EEC) are recorded.
From legislation.gov.uk's record of changes, the official one: see it there.