By 1967, Fiat was leading the European market, and its 50th anniversary was coming up. For the occasion, a new series was developed in Turin with more innovative characteristics than earlier models. The new series would be based on the Diamant series, and the name chosen was "Nastro d'Oro" or "Gold Ribbon", marking the Golden Anniversary of Fiat's "marriage to the land".

The appearance was a strong evolution of the Diamant series, again penned by Pinninfarina, with the longitudinal ribs of the engine cover now more predominant, and running though to the nose conferring lightness and movement. The colors were slightly changed as well, with a lighter orange for the bodypart, and blue for the mechanical parts, which gave the impression of a dynamic and modern machine. 

The new series wasn't only a styling exercise though. The series introduced new upgraded engines, all now with direct injection and rotary injection pumps, and all but the smallest reverting to a stressed crankcase design. Improved driving ergonomics, a number of new safety features including a lock preventing starting the engine while in gear, new 12 volt electrical system, upgraded gearboxes with synchronizers, and the control-matic three-point hitch now standard on all models, are just a few of the technical features to mention.

Some sources tell, that all models at launch had the option of a Frutteto, Vigneto and Granluce variant, though this has been difficult to confirm.

The first models of the "Nastro d'Oro series"/"Gold Ribbon series", were put into production in 1968.

The 400's were sold internationally and domestically as Fiat. Apart from France where they sold under the Someca brand, and North America where the 420 (1978) and the 480 (1981 to 1984) sold under the Hesston brand.

All models used a stressed chassis design, with the engines cast-iron crankcase being part of the tractors backbone. 

The gearbox differed depending on model and options. The 400 and 450 came with eight forward and two reverse, while the 450 Special had the option of a nine forward/three reverse. And the 480 could be had with either a six forward/two reverse or eight forward/two reverse. Half of all forward gears were syncronized on the 400's.
All models came with locking differential on the rear axle as standard, and was offered with draft control / "Control-Matic".

All but the 480 used a three cylinder version of the 250's engine. The 480 using a three cylinder version of the 300's engine. The engines were watercooled, direct injected diesel engine with stressed crankcases, and displacement from 2.339cc to 2.592cc.

The Gold Ribbon Series tractors enjoyed even greater success than its predecessor, being recognized for their new design, engines and features.
In 1968 alone, when the European market was contracting, Fiat produced a total of almost 60.000 tractors, 42.000 of which in Modena alone, 5.000 more than the previous year. That year also saw the production of the 500.000th Fiat tractor since 1918.
Such succes was the Golden Ribbon Series in fact, that the 480 and 640 are still manufactured in Pakistan in the 21th century, as a simple and reliable workhorse for farmers in the region.