If going to Penn Mac in person, be sure the bag you buy has the Grande logo on it. We went there a few months ago to buy the 50/50 blend. I asked for the Grande 50/50 blend, not knowing what the bag looked like. What I was handed was labeled "Wisconsin's Finest" and had Penn Mac's name on it, and it was short dated. It was about as good as supermarket shredded cheese. But I kept the bag it was packed in.
I just saw a bag of Savoldi 50/50 blend at a foodservice distributor. Same Pennsylvania USDA plant number on it. Turns out the cheese was either manufactured or shredded/packaged at the Dairy Farmers of America plant in West Middlesex, Pennsylvania (the old Savoldi Cheese plant now owned by DFA).
Since PennMac is listed as a member of Bellissimo Foods, it seems that PennMac has a division serving restaurants and institutions, in addition to its fabulous shop on Penn Avenue in Pittsburgh's Strip District.