90% of 127's were made in this configuration ---http://www.accordiongallery.com/giulietti-cl127T
When Julio made the decision to import a fine line of accordions and market them with the family name, he first went to to the firm of Serenellini in Italy. The Serenellini made Giulietti's were a well made box but Julio wanted a box superior to the at the time (60's) accordion models from Excelsior, Sano, Titano and Petosa sold in the US. To accomplish this he then went to the firm Zero Sette of Italy to produce a line of accordions superior to his then competition brands sold in the US. The merge of Giulietti and Zero Sette then produced a exceptionally fine line of accordion models that were, and still are, much sought-after today.
If your badge on the center of the grill is a "Treble Clef" it is a Serenelli product, and if the badge is a "G" you have a superior Zero Sette product. Classic 127's (depending on condition) will fetch from $2000.00 to $4000.00 USD in today's market.
P.S. The accordion in the Pic's are of a Zero Sette product.