The 6-cylinder units shared the same 120mm cylinder stroke length, but the bore (cylinder diameter) on the larger engine was increased by 5mm to 80mm. Although a new more modern Vivastella was introduced for 1934, the earlier model continued to be listed, at an attractively lower price, in the catalogue.
The 6-cylinder units shared the same 120mm cylinder stroke length, but the larger engine's bore (cylinder diameter) was increased by 5mm to 80mm.  A newer, more modern Vivastella model debuted in 1934, while the older model remained listed at a lower price point in the catalog.