4-String Banjo Chord Chart and Tabs in Whole Step Down Tuning

GbmM7, Gbm#7, Gb-M7, Gb−Δ7, Gb−Δ, Gb minmaj7
Notes: G♭, B♭♭, D♭, F
8,8,9,10 (1123)
8,4,5,6 (4123)