I believe it was 99. Mine are actually the smaller piston ones. The back side - the cooling fins and casting around the pistons I think are different, along with the piston diameter.
A friend bought a set from a guy on ebay, and he got one of each style. We negotiated with the seller to send another mis-matched pair and I bought the older style from my friend.
I have an 02 gt that I put the mach 1 calipers and rotors on off a wrecked car , and it greatly improved the braking on it so im sure its worth the extra money on a fox as well ......
Thanks guys. Yea, right now I have all 99 GT brakes on my car, so hopefully I'll see a nice improvement. Not I just gotta shop around and find some decent prices. StangSuspension.com has free shipping going on now, so I might junp on that.