Re the expansion tank, yours is a 2wd and the tanks on eBay for 60-70 quid are 4x4 tanks which you can fit but you need the adapter hose kit for an extra 20 quid I think. I thought about changing mine but decided to stick with until it leaks. The 2wd ones pop up on eBay now and then for comical prices. I think one made £1500 earlier this year!