Rip off in progress!
When you say leak, how bad? Your boat should be using the carbon ring seal. There is a rubber boot that has a carbon ring in it, that rides up against the seal collar on the shaft. Pull your boot back and look at the mating surface of the stationary carbon ring and the stainless collar on the shaft. It may just be dirty. Clean it up a bit.
If it's not leaking all so bad and you got an auto bilge, 450 gph or better, don't bother...........:cheers: