i am looking at buying a cylinder. Its advertised as a 2003 / 2003 yz or wr 450 cylinder head. The part number for the 2003 YZ 450 cylinder is 5TA-11311-00-00 The part number for the 2003 WR 450 cylinder is 5TA-11311-10-00 (replaces 5TA-11311-02-00) they are close but not exact. Does anyone know if the '03 WR cylinder is interchangable with the YZ450 cylinder? If not does anyone know the difference between the two?