The 6191 Streamliner was the natural-finished variant of the 50s Streamliner series. All three Streamliners were descended from the earlier 6190/6191 Electromatic. Much like the Country Club name supplanted the Electro II in 1955, the Electromatic became the Streamliner. Very early Streamliner, like Country Clubs, retain the clear plastic knobs common to the Electromatic/Electro II. The Streamliner changed considerably in 1955, benefitting from the introduction of a gang of new Gretsch models. The spruce top was changed to maple laminate, a G-Cutout tailpiece replaced the earlier trapeze-style, and the body was now 2 3/4" thick. These '55 to '57 models are built on the exact same body as the 6120 Chet Atkins of the era, and are effectively a single-pickup version, without the tremolo, binding or other frills. Gretsch didn't exactly advertise that fact, though. The Streamliners were much cheaper than the 6120 when new. They still are. Those changes created the definitive 6190 Streamliner. From there, the only significant change was a switch to FilterTron pickups for '58, in common with nearly all Gretsch electrics. It was discontinued in late 1958.