I just got a 2003 yz450f and the kick start holder is broke on the right crankcase. I know its not advisable to mix and match cases, but i was wondering what years i could use the right crank case from. I looked on partzilla and the 03 cases are a different part number from the 04-05 cases. When looking here on thumpertalk they have different old part numbers, but the new part numbers is the same. Is there something major different about the two or can i use a 03-05 crankcase and be ok?