which ones do i need? its a mk2 with a mk3 gt rear axle.

From GSF website:

65462B - WHEEL CYLINDER-RE 15.8 BQ - PO (Without Brake Pressure Regulator) 2/85 >7/94

65463B - WHEEL CYLINDER-RE 19.0 BQ - PO (With Brake Pressure Regulator) 2/85 >7/94

They are two different sizes.

Not sure what it means by brake pressure regulator?? Where would it be if i had one? Can anyone shed some light?

if you've just changed the rear axle then its unlikely you;ve got the pressure regulator. if you have one ots on the passenger side just in front of the back axle, its a valve that the brake lines go through.

na i aint got one of them then.

Why would having one mean you need different wheel cylinders though

because if you've got a regulator then you have bigger cylinders to go with it. IF you fit the bigger cylinder without the regulator then the rear wheels will be over-braked.

The regulator decreases the bias to the rear brakes and gradually increases it when you've got more weight in the back of the car. But lowering the car fucks it up as it thinks the lower back means it is heavier. Doesn't really cause a problem though.

ok, thanks for the help guys