Blower Motor and Resistor Part no

Been having problems with our heater motor cutting out when turning right a problem many people have failed to sort out so I have decided to replace the blower unit, so today I took mine out and the part no are 1k2820015G and the resistor 3CO907521F, I have found some replacements on a well known auction website the part numbers match but the last letter are different, does anyone know if the letters denote a year or do I need an exact match? seen a few where the letters are one back so for example it was 1k2820015F.  Your help would be much appreciated.

Edited 26 July, 201411 yr by chopsie73