I don't know what V drive unit your boat has, but the walters v drives have dain plugs like shown in this link
http://www.tigeowners.com/forum/show...on-and-V-Drive
Otherwise removing the inlet and outlet hoses should let out any residual. To be extra safe, you can always fill with rv antifreeze.
Every time I have pulled the water drain plugs on my rig nothing comes out.