Door lock mechanism part number question

Guys / Gals - a little part number help requested.

I have an 02 1.9TDi elegance estate with the not uncommon door lock mechanism problem. The near side front locking mechanism is playing up. I have previously taken the thing out and taken it apart, and am about to try it again, this time concentrating on the connections to the motor unit as mentioned in another post (have previously re-soldered all joints and checked micro-switches).

Anyway assuming I can't fix it, I thought I would keep my eye out for a secondhand locking unit. My local skoda guys gave me the part number I need of "3B2 837 015 AK".

I understand the basics of part numbers, but am not clear on the significance of 2 letters at the end. Will I have to find one with exactly the same part number, as there seem to be quite a few with the same first 9 digits but differing letters at the end.

Or could there some that are compatible and some that aren't and if so anyone know which ones?

Thanks as always