Ford wanted to pickup lagging sales due to the redesign of the T-bird from a two to a four seater. Also Ford wanted a capable sports car with room for a small family at an affordable price.The Mustang became this car. The Mustang was an instant success. They out shot their original sells goal by 400,000 units in the first year and half. Selling over 500,000 by 1965. The reason for the success was the cars performance and cheap price, costing just over $2,500 fully loaded. In its second year there was a new body style and two new options added. These being the fastback body style and the GT and GT-350 options.
The GT option included a 225 bhp 289 cid. V-8 with the possibility of moving up to a 271 bhp 289. It also was included special chtrome accents, fog lamps, and a five dial gauge cluster. This was available on the convertible, coupe, and the most popular, fastback 2+2. This package was also included on the Shellby GT-350, a very special version of the GT, with many engine and suspension modifications. The GT-350 was available by special order through specialty Ford dealers. Most of the GT-350s were put into race duty. A team of GT-350s was entered into the Le Mans racing series and they won the series championship two years after they were allowed to race in the series. The GT and GT-350 remained essentialy the same except for minor changes in engines and suspensions until the whole line was redesigned in 1969. Until 1968 there were no new models introduced, this new model being a GT-500 with a 428 cid engine.
In 1969 Ford added the Grande to the Mustang lineup. It was added to cater to the luxury needs of performance enthusiasts. This year the Mach 1 and Boss series Mustangs were also added. The Boss Mustangs were added to allow the body style and engines in Trans-am and Nascar racing. The Boss 302 was used in SCCA Trans-am racing. While the Boss 429 was used to get the 429 cid engine into production use,in order to be used in the Torino Taladega cars on the NASCAR circut.