In forklifts the serial number does not directly reflect date of manufacture, as a general rule. (some brands have some models that do).
We usually have to look it up in a serial number ID book, or to contact the manufacturer, but on all forklifts sold in the USA, since 2004, there is a sticker on th motor that will tll you the motor's month of manufacture (as long as it is the OEM motor, not a rebuild, still installed)