you just need to know what you are buying. it will be a ntc brand valve, you can buy that in sgp packing or ntc paking (both are the same thing, sgp is overpriced).
it is a common item. try the molvis (shakeel autos township). or if montogomery rd is near, visit mumtaz autos.
once you have bought it, put it in a sauce pan full of water, as it approaches near 82 deg c, it will start opening up.
if it has opened up , then remove the water and let the valve air cool, it should shut.
this will make sure that the new valve is not stuck closed.