WOAH unless you want to be really stripping the whole diff DO NOT grit blast it All it really needs is a gunk and stiff brush mate.
You could end up making a simple job into a whole rear bevel box rebuild and than some.
You can clean everything off the swing arm with a wire brush on a drill, far safer than grit, IF you grit it you will then need to replace the bearing and really really clean it.
The fillers are either an Allen Key OR on older ones a BIG brass nut, 22mm spanner for that one the drain is I believe 19mm (May be 17mm tho’ gerrin old y see) The filler SHOYLD have a small rubber bung in the top to stop crud gettint in and ruining the Allen key socket 'ole
Gearbox level plug on right kinda behind the footbrake
Gearbox drain plug is underneath look and you will see the obvious drain plug
Haynes manuals often 2nd hand BUT Haynes DO give Club Members a discount
Swing arm is fairly easy
Undo silencers
Rear wheel out
Undo bottom of righthand suspension
Bevel box off
Left hand suspsnsion lower off the arm support the swingarm
Take off the large outer lock nuts on each side
On my older V1000 I take off the rear footrest plates as the 17mm nuts and bolts do protrude making getting the swingarm out more difficult
You can also get a bit more room taking the silencers off
MEASURE the distance the fine threaded swingarm bolt protrudes IT MATTERS
Undo each side carefully I count and note the number of turns
Undo the rubber boot held on with 2 jubilee clips
The swing arm will then jiggle free,
I can’t remember if you need to take the centre stand out!!