I am going to replace the leaking cylinders on my rear drum brake with newly bought cylinders with bore Ø17.46mm which the website said it fits my car. However I happen to notice there're two different specs: bore Ø17.46mm and Ø15.87mm (my JDM GD1 is currently equipped with this smaller one, I think). I don't bother to return if the Ø17.46mm cylinders are good on my car too. Does anyone know and help? Thanks.