Hi Mark
I don't think the numbers have to match exact
there revision numbers, as they update them the letters and number go up
at a guess the xw4t will be a earlier revision and the 2w4t will be a later revision of yours
they usually need programing if there new, but if the car its comes off has the same spec as yours, it might work straight away
try dennis on here for parts "the jag den" he might have one
also have you checked the wires in the door shut, they do snap there
cheers
joe