On the subject of lubricating the splines? If you don't want to bother taking the shaft off the gearbox output shaft or, even if you just want to do a bit of maintenance in between bearing greasing events, you can use chain lube with one of those applicator spouts for the front splines. Just snip the cable ties that hold the boot to the swingarm and peel it forward, then poke the spout in and spray some chain lube around the yoke and splines. All chain lube is is sticky grease suspended in a volatile liquid. It will quickly flow down the splines and then the volatile carrier evaporates leaving the lube on the splines.
At the front the splines don't really slide but the grease keeps moisture off so the splines don't rust and erode. The rear yoke it slides as well but dropping the bevelbox off is no big deal to access it and it doesn't need doing very often.