The unique features of the Mustang make it a unique guitar.
The Mustang features two single coil pickups with an unusual switching configuration, and a unique tremolo system. Though the body shape is similar to the Musicmaster/Duo-sonic. By 1969 the body shape changes from a slab to an offset and contoured style.
The white model came with a tortoise shell pickguard and featured white covers on its slider switches. The bodies were either poplar or mahogany. The necks headstock was larger than the one found on Stratocasters of this era. The Kluson tuning keys featured white ovular knobs. There was one string guide on the headstock. The guitar had a chrome control plate for the volume and tone potentiometers and cord input.
The Mustangs slider control could just be off or on or the phase (or magnetic flow) of the pickup could be reversed. This would not just create a unique sound, but could get rid of that pesky 60 cycle hum since one pickups signal was inverted from the other.
Aside from the pickups, the other unique feature found on the Mustang was its unusual tremolo system called the Dynamic Vibrato system. The design was different than any other Fender vibrato. The key to the bridge/vibrato was a heavy chrome plate.
By 1967 the guitar was offered in a variety of colors and the competition model was introduced. The competition model had a racing stripe across the lower bout. The competition model was discontinued in 1972.
By 1984 interest was waning in this guitar and production halted.
The Mustang experienced a revival in the 1990’s when Grunge bands picked up old Mustangs, Jaguars and Jazzmasters.
Kurt Cobain asked Fender to design a unique Mustang with a body shape that combined features of the Mustang and the Jaguar. This was offered for sale by Fender for a few years and called the Jag-stang.
Fender also offered a Mustang Bass. This was produced in 1966 as a companion to the Mustang. It featured a 30” short scale neck. Just like the larger Precision bass, this guitar came with one staggered split pickup in the center of the body.
The original models came with a string mute. Most players removed these. So Fender quit offering the mutes on later models.
The Mustang Bass was offered until 1981. It was replaced by some other Fender products including the Squier Musicmaster bass and the Bronco bass.
One year when he became ill and confined to bed for several months, he asked one of his band buddies to lend him a guitar. By the time he was well he became more proficient on the guitar than his friend. Steve changed his name and has gone on to be a guitar legend as a player for King Crimson, Zappa, David Bowie and others.
Belew asked Fender to design a customized Mustang for him. He had three of them built. They have three pickups with different colored covers that were made by Don Lace. The control switch is on the upper bout. The guitar also features a built in Roland GK-2 synth pickup with separate controls. The design on all three is different. Belew states he likes the Mustang because of its short neck.