Tommy, the #310 was made in Sidney Ohio after Wager purchased Griswold and their patterns. They lack the Erie Pa, Usa on the base and the lid will be missing the Erie. The slant Griswold lid minus the Erie and pattern number is correct for it. They show up on ebay quite often.
Troy, so as I'm looking at the markings, they followed the skillets. Erie, then slant Griswold with Erie, then slant Griswold EPU, then block. That's really something to see them laid out in a row so to speak. Thanks for posting.