You are correct on the differential fluid and not needing the FM in a QT II XK. You have a NV245 which I've found takes a little less then 2 quarts to fill. As for the mileage on the waterpump, I was actually thinking about changing mine soon. I have about 85,000 miles on my XK and was purchased brand new. I've found them for a decient price at the local auto parts store for a lot less then what the dealer wants and it even has a lifetime warranty. Its a new water pump, not a reman. Id recommend replacing the thermostat while your at it.