About LEGO Universal Building Set
LEGO's Universal Building Sets theme was released as early as 1966 but it was not until 1973 that the Basic LEGO sets became known as Universal Building Sets. These sets were produced in two set version numbers, the first was for sets that were sold in the UK, Europe, Canada and Australia. The other version numbers, but for the same exact set with the same box artwork was released in the United States. Most, but not all sets between 1973 and 1981 were sold in both regions.
1977 LEGO Sets
1977 introduced the Expert Builder series—precursor to Technic—using beams, axles, and gears for mechanically rich models. Town-style sets broadened everyday subjects with houses, shops, and vehicles. Dedicated Space and Castle themes were still a year away, but elements and styling hinted at their imminent arrival.