Can you mix and match the older cranks with the newer crankcases? Or is it the other way around? Basically, I'm wondering if I can put a 1984 crank in a 1999 crankcase. Which crankcase is better for the survival of the crappy bearings that Yamaha installs on their crankshafts? I love the motors but they seem to eat bearings. Any advice would be greatly appreciated.