Had to change the rear pads on my 05 jag. After I recieved the new pads from the auto parts store I realized that they were smaller than the pads I just pulled off of the car. I took the old pads back and after some searching they realized that they were pads for an 04.
They gave me the correct pads, which worked on my vehicle.
My problem is that my jag is an 05, not an 04. Would there be a reason that the calipers would be from an older year car? Should I expect the front calipers to have the same issue when its time to change them?
The car has the original rear end if anyone is wondering.

 

Harry, look at the build date of your car (sticker is located in the drivers door opening). I bet you will find that it was built in early 05. Quite often, on the cars near the end of the year, beginning of the year, when the parts become short, they start borrowing. So, in the case of your car, they had "extra" calipers from 04 left over (or the 05 calipers had not shown up yet), so, they used the older calipers on the year newer car. I had an 86 T-bird with a lot of parts from an 87 T-bird motor. Made finding parts a real "joy". What made it worse was not even all the parts were from 87, some were from 86. I ended up having to take the old part in with me so I could be garanteed to get the correct part when getting a new part. The guy behind the counter began to get to know me pretty well and we turned it into a game.

 

Someone had mentioned 04 brakes on their 05 previously, so I don't think yours is a completely isolated incident. If you have an early 05, it's possible Jaguar was just depleting their left over parts before switching to the new pad design.

 

I've noticed almost everything associated with our cars are by build date.

 

I had same prob with my 05sport. I did a complete brake job when I bought it, with new rotors, pads. I went to replace 1 caliper and it was bigger than what I took off so I replaced both with the larger on rears. So I guess there is a date thing at work here