The third evolution of the First Generation Ford Mustang was the 1969-1970 Ford Mustang. This updated Mustang was longer and heavier than its predecessor and was offered in Hardtop, Fastback (known as the SportsRoof), and Convertible body styles. These Mustangs were available with two inline six engine options as well as a variety of V8 options, which were paired to manual or automatic gearboxes. The 1969-1970 Mustang was built in a wide range of variants, including the Base Model and GT. The GT was only offered for the 1969 model year due to the introduction of the popular Mach 1 performance variant. Offered alongside the GT and Mach 1, high performance variants such as the Boss 302 and Boss 429 were used in order to homologate certain engines for motorsports, leading the creation of cars such as the Boss 302 Trans Am Race Car, and as well as other Racing Cars. Due to the Mustang's popularity, it is common to find highly modified Custom examples. The 1969-1970 Ford Mustang was replaced by the 1971-1973 First Generation Ford Mustang.