Unless the label is signed, I would go on the assumption that it was not made by Manuel Contreras personally. In 1972, he had at least three qualified luthiers working under him, including Ignacio Rozas, making his higher models. Like most makers in Spain who have their own retail shops, he also sold a line of factory guitars under his label. Usually, such models have a distinctive label and headstock to distinguish them from ones made in the shop.
Zavaleta’s La Casa de Guitarras