Abstract: A finishing monoblock with optimised transmission ratio for a billet rolling plant comprises a plurality of rolling stands (G1-Gn) arranged in sequence suitable for forming a rolling line and actuated by a pair of mechanical transmissions (11, 12) in which bevel gear pairs are foreseen for the variation of ratio in the stands of the rotation speed of rolling cylinders (18). According to the invention, such a variation of the ratio in the stands is carried out through the combination of a first type (A, B) of bevel gear pairs with a second type of bevel gear pairs (C, D) and there is a set of four of cylindrical gears suitable for making four stands (C, D) with the same transmission bevel gear pair.