The 1331 amplifier was the bottom of the line of the alligator/tweed 133X models. It was as basic as you could get, and still retained the style of the line. By now, only the long-lived multi-line spanning 1330/1430/1390 cost fewer dollars and had less 'amp' for your playing pleasure.
1331 basic is this: 8 inch speaker, volume/tone, two inputs, 8 watts output. Sound-wise, the 1331 was a little limited in its dynamic range, with a rated frequency response of 100Hz to only 9,000Hz.
Fall/Winter 1954 at $39.95
Spring/Summer 1957 at $39.95