My 01C X77 booster (owned since 1973, removed from car in 1980) is dated "2" , 9204, small font, "Delco Morraine" upside down under the vacuum port , absolutely original to the car. Almost too good of shape to be sent out for replate - plating is faded but pretty decent (likely due to the fact it hasn't been on the car for 32 years).
Regards,
Steve