I have a ES335 in tobacco finish. it has the serial number 440124 stamped on the headstock, but no 'made in America'. The 4th digit is unclear, but likely a '1'. Looking through the 'f' hole, I can also see that the label inside is the purple / black triangle / rectangle design. I purchased it second hand in 1992 and was told then it was from around the 70's. I've really struggled to establish its exact date of manufacture. Can anyone assist?