Coolant pump identification help required

Hi Folks,
Could anybody tell me if a V12 single V pulley “pump” (JLM 10819) is suitable for a 1981 XJS 5.5L HE.
I have spotted one for sale with the above code and description, but the add states 1982 onwards.
Is there a difference between a 1981 pump and a 1982 onwards pump ?
Many thanks for any help provided.