Throughout the 1960s, the premium Fender guitars were the Jaguar range, equipped with the floating tremolo . By the early 1970s, it was obvious that most guitarists preferred the cheaper Stratocaster, regardless of price and supposed quality and prestige, and particularly liked its tremolo arm design. The Jaguar and indeed all other Fender guitars using any tremolo design other than the synchronised tremolo were for a time withdrawn, to return to the catalog as classic or retro models in the 1990s.
It was also notably used on the Jagstang, a custom design by Kurt Cobain combining features of the Jaguar and the Mustang. Some late 1960s Mustangs were fitted instead with the floating tremolo , which was promoted by Fender as their premium unit, but later Mustangs returned to the Dynamic Vibrato.
The original production runs of the two overlap by more than a decade, but the mechanisms are quite different. The existence of a few 1960s Mustangs factory fitted with the floating tremolo has probably added to the confusion. The concealed mechanism is in a chamber of a completely different shape and position, requiring an impractical amount of woodwork to convert from one to the other, and the mounting plate is of a different shape with different mounting holes.
Source: Wikipedia > Tremolo Arm
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