That model of Major used 3hp, 4hp or 5hp Briggs & Stratton engines. The 2hp and 3hp B & S had that square plate on the fins above the crank pulley so, as Wolseley didn't fit the 2hp it has to be a 3hp. That Major badge with parallel lines on it was used from about 1973 to 78 but the 3hp was dropped in favour of a 4hp in about 1976