 Since the tube complement was the same, Fender just used up their stock of printed tube charts saying AB763 until they ran out.The earliest silverface Twin Reverbs, along with all other silverface models, had an aluminum frame (trim) surrounding the sparkling blue grillcloth from late 1967 to 1969.Early silverface amplifiers made between 1967 and 1968 had black lines on the brushed aluminum faceplate, still retaining the '60s "tailed" design on the amp logo, installed on the upper left side of the grillcloth.