G-flat6 guitar chord is also written as G♭6 or G♭M6.
Guitar chords chart for G-flat6 chord with suggested finger positions on the guitar fretboard is shown below.
View 6 chord for guitar with other root notes
C - D - E - F - G - A - B - C♯ - D♯ - F♯ - G♯ - A♯ - D♭ - E♭ - G♭ - A♭ - B♭