SJ Driveshaft Identification question

[Kny21]

Got a driveshaft here for my SJ that has the pump end of the shaft where the bearings sit hollowed out a good 4" or so. My stock one that broke is solid and other's that I have seen and believe to be stock were solid too. Anyone know if this is a non-OEM model, just a modded shaft, or what? And if modded what would the benefits be? I'd assume just lighter to assist with quicker revs, etc. but not really sure.

Thanks,

 

[tricky1]

its OEM....Some are hollow.

 

[Kny21]

any certain reason? almost wouldn't make sense for Yamaha to go the extra route and hollow out since the material is already there.

or is this one of those things we'll never know like why the motor mount washers have that cut-out. :dunno: