I am trying to swap bottom ends on a 2008 250 Big Bear. Per the attached picture can anyone confirm if I have to unscrew the large nuts on #4 to remove the bottom end? Thanks, I just wasn't sure if this secured the engine at the
u-joint and I didn't want to unscrew if it's not necessary. Thanks

 

What exactly do you consider the "bottom end"? #4 are the swing-arm nuts per the manual...

 

Looks like Yamaha think you need to remove the swinging arm to get the prop shaft out of the transfer box. You can get most engines forwards far enough to get the shaft out without doing this, but the writers of the book should know what they are on about.