In Europe, 2 new models, a small go-cart and a large crane, as well as a new supplementary set were released. The theme was finally released in the US under the name "Expert Builder" and were given 900 series set numbers. The initial release included 4 models, the motor set and a supplementary set. This difference between US and European availability has become standard Lego marketing practice, in fact there has never been a year with a common retail Technic assortment.

In addition to the new 16t gear, chain links and gear reducing blocks were introduced in set 872. The blocks connected to the 4.5 V motor and allowed for a 1:20 gear reduction in a much smaller space than would be required with Technic gears.

1978 US ad