I've got a small collection of new take-off flywheels from a defunct Ford Industrial Distributor and a one I obtained I strongly believe is steel since it came off a serious race motor w/scatter shield.
None of the flywheels have any casting marks, integral counter weights or numbers and look to all be 100% machined making me believe they are steel.
They're all internally balanced FE or 429/460s,
Kind of odd but the brand new steel and alum flywheels I have only have SEMA sticker's that are far from permanent. Maybe stamping IDs into something you don't want to explode is frowned upon?