Introduced in 1965, the GT Series was Martins second true electric guitar series - replacing the F-series models. The Martin GT-70 model was made from 1965 to 1966 and has a semi-hollow plywood body with f-holes, bound 22-fret mahogany neck with rosewood fretboard, chrome hardware, two exposed DeArmond pickups (with adjustable pole pieces) and a Bigsby-style tailpiece. The large, bound, non-traditional Martin headstock has a logo decal and 3-per side tuners.. The GT-70 was available in black or burgundy red finishes and only around 1,450 were made in total.