1969 B-body - it's the STANDARD spring on a '69 V8 Charger & probably included with a 383 on Satellite and Coronet (non-performance non-SB/RR)

there is a 4-digit date & 5-digit vendor number also stamped on them - what's the date?

the part numbers in the Parts Catalogs are for "leaf spring assemblies" and differ from the numbers stamped on the bottom leaf