have a Gibson J40 pinless bridge acoustic guitar with gold Grover tuners. I thought my guitar was a 1970-73 model because there's evidence the tuners were replaced. But there's no accurate dating system pre-1977. So, according to the post 1977 8-digit dating system (SN
7318
7097) it would be a a 1977 model. The label says "Union Made" in Kalamazoo, Michigan. Supposedly it was the
97th product out the door. The 318 supposedly means made on March 18th.
FWIW it's a pretty neat guitar but sounds a bit bright for my tastes. I bought the guitar in 2009 and didn't play it very much at all. Honestly I was skeptical; figuring the pinless bridge might be too fragile. It came to be more of a conversation piece that cost me more than it should have.
I never took it outside. The neck is straight. The frets are in great shape. There are no scratches or belt marks on the back. There's no checking. There's no bowing, no armpit stains, no beverage stains. In my adult beverage world that's astounding.