I have heard of coins changing grade even while slabbed, due to previous chemical contact that went undetected. And, grading has changed over the years. So, do ou think you will get the same grade? Of course the fair thing is to go with its real grade, but is the coin at risk of going down? We have so many intermediate grades now that were not there when I started. EF was EF, and AU was AU, and no multiple MS numbers. You did say an old slab.