What's the easiest method to do this? Do you just remove the driveshaft to grease it, or is there an effective shortcut? This sounds like it could be a shared Gen1/2 thing.
You have to unbolt the driveshaft at the pinion flange (be sure to index mark it first) and then slide the slip yoke out from the transmission. The grease is then applied to the splines inside of the driveshaft slip yoke.