I bought our 85 GMC Sierra brand new in October 1984...never heard of this option.
The gun case in the photo is a Gun Guard...very well made product.
1972-73 in high school we all had shotguns or rifles in our cars...but we were just going hunting. Drove to school everyday with a gun in the back of my father's Chevy wagon...today they would have a SWAT team, helicopters and all the major news outlets in the parking lot
How times have changed