I just received my dad's Gibson ES 150 guitar from my older brother. It has been its case since my dad died in 1968. He was the only owner. I see stamped on the inside of it the number 4488 25. I assume that references the year it was manufactured. Anyone have any idea what year it is. I know he played it for many years. It has trapezoid inlays. I don't think anything was ever done to it, and I know it's been in its original case for the past 51 years.