The PL section was definitely used on very old safe deposit box locks with peanut cylinders. I have one from around 1905-10 that uses this blank. The renter’s keys are PL, the guard a corrugated keyway. They’re for a .40 cylinder, marked “PL”, and 5 pin in length. I have some marked “Yale Paracentric” with no keyway marking, but they are definitely PL as well. Perhaps you could rekey those padlocks to safe deposit keys if you can find some.