A stringed musical instrument having an elongate neck and a body which may have a resonant cavity at one end and a head at the other end thereof. Strings extend across the neck and, when vibrated, generate musical sounds. The invention relies upon fingerboards which are removable so that one type of fingerboard may be substitutable for another type of fingerboard in order to generate sounds of different timber or of different qualities. Thus, fretted fingerboards are substitutable for non-fretted fingerboards. Moreover, and in a preferred embodiment, the fingerboards are inserted onto the neck of the instrument and can be slid into and out of interlocking elements from one longitudinal side of the neck of the instrument. In one embodiment of the invention, dovetail projections are formed on the neck of the musical instrument and corresponding notches or grooves are formed on the underside of the fingerboard to permit an interlocking arrangement of the fingerboard on the neck of the musical instrument. Compensation in the thickness of fretted and non-fretted fingerboards is also provided to insure that the string of the instrument is only moved the same distance with either fingerboard.