I have lots of those kind of slabs.
You sure it's more rare then a Dolly?
Look closely, I'll bet you don't have more than one or two. PCGS on the top of the green label, with label edges rounded and not preforated, 4 pins, two piece slab with the PCGS on the outer ring. They were used for a brief period of time in Dec. of '89, IIRC.