If you have a leak through the transom assembly, you should replace the driveshaft bellows, shift shaft bellows, exhaust bellows, gimbal bearing and shift cable if it has not been recently replaced (will most likely break trying to change the bellows anyway). You will also need an outdrive gasket kit to put the drive back on. This will save you a lot of unnecessary work in the future. Not a job recommended for someone who isn't very mechanically inclined.
Greasable universal joints are a thing of the past, so unless your boat is ten years old or older don't worry about taking it apart to grease the drive shaft. Keep the gimbal greased though!