Josh, If you find that the expansion tank is leaking, I would personally go for a new one. There would not be much difference in the cost. There are several other suppliers of genuine Jaguar parts as well as Just Jags, -- the David Manners Group, and there is also a Taunton Jaguar dealer, although I am not sure of the exact name other than Taunton Jaguar. In the days when I got my hands oily, I did change a water pump on my wife's Mk 3 Viva which also included the expansion chamber, which only took an hour. You will have no trouble. Regards, Peter.