Volkswagen's part numbering scheme
Each part number is composed of nine numbers in three groups,followed optionally with a letter suffix:
vvv ggg ppp suffix
Vehicle type (vvv):
155 = Convertible
171 = Golf I
161 = Jetta I
165 = Jetta II
191 = Golf
261 = 16V GTI
531 = Scirocco I
535 = Scirocco II
Primary index (ggg):
100-199 = Engine/Cooling/Clutch
200-299 = Exhaust, Fuel Tank
300-399 = Transmission/Transaxle
400-499 = Front Axle/Suspension
500-599 = Rear Axle
600-699 = Brake
700-799 = Cables, Bumpers and Foot control
800-899 = Body/Interior
900-999 = Electrical, ignition, fuel injection
Individual Part Number (ppp):
000-999 = Individual part
The primary index and the part number are the most important numbers because many of the cars share the same parts. So do not be surprised to see a 171-Rabbit type part in a Jetta.
Note that some part numbers are exclusively related to certain parts of the car.
For example, vvv = 020 are related to the transmission.
