What Wheel Cylinder??

I wanted to find out how much a wheel cylinder would be for my car which is a 83 Mk1 GTI and VW gave me the following 3 options:

All models without brake pressure regulator 1H0611053B

All models with brake pressure regulator 6N0611053

All models 6N0611053

2 & 3 are the same part number so i don't know what the difference is?
Anyone know which one is for my car?
Cheers

This model:

All models with brake pressure regulator 6N0611053
All models 6N0611053

If yours is a Gti then nit has a pressure regulator as standard - also known as a brake compensator (see braking FAQ)

Basically there are two sizes of rear wheel cylinder…

14.29mm on cars without rear pressure reg
17.46mm on cars with rear pressure reg

Rule of thumb is if its got solid front discs, it has the smaller rear wheel cylinders, if its got vented front discs it has the bigger ones.

Obviously yours has the vented front discs being a GTi, and has a rear pressure reg so you do need the bigger 17.46mm ones.

The ones from VW (6N0 611 053) will be different to the ones that are on the car now, as these are the machined Aluminium bodied versions that are from the later Polo, instead of the old cast iron ones on the Mk1 Golf.

They are interchangeable, the only difference I have found is the new style ones only use one of the two existing bolt holes to hold it to the back plate.