I managed to trash the lower unit on my 2001 BF50A. Hit something that broke off the one side of the ventilation plate and bent the prop shaft. I have a new lower unit to install but the new one is different where the shft rod enters the top of the case. The old unit had a white plastic fitting that the boot attached to. The new lower unit has what looks like a seal but no place to attach the bottom of the rubber boot. Do I need a different boot or is the seal adequate to keep water out ? Many thanks for the help.