The header tank in my sapphire cosworth looks the same as the ones in a 3dr and because of that they appear to be commanding comical prices on teabay... My mechanic has suggested replacing it as it has hairline cracks in (even though it still works fine just now).

What are my options? I can get a new one for a 4x4, can it be made to fit? What exactly is the difference? I don't want an aftermarket looking item if possible as the car is standard.