Hello Alfie,
Your washer pump is correct.
There were (according to my vague memories) three different series of pumps for our cars,
and of course only the last one (the A108 869 0121) is today available - a very common practice for MB parts.
If you still have the original one, be happy since these are more or less not more able to come by.
BTW, on the metal back lid of the pump chamber of the whole unit there is usually a "VDO" inscription and a production date (something like 11.66) visible.
Enjoy !
Best,
Achim