Hmm, I did mine last summer but on a manual gearbox so not sure all this is applicable?
there's a good instruction video on youtube by James Aker 'Sir Adventure' for changing it on a manual box
you need a few extra tools to make it go smoothly:
-oil resevoir/funnel with long plastic hose to insert into gearbox fill opening - it's way too far to try to pour and of course the opening is on the side..
-correct large hex key insert to remove the plugs (got mine from Brickwerks I think)
-a new plug (optional also from Brickwerks)
getting access to the gearbox fill plug wasn't simple - first the gearshift connection was in the way so had to drop that, and then hex key insert/socket wrench combo was slightly too long and hit the exhaust system. I carefully clamped the exhaust just enough to give me a few millimetres of room to get the socket combo in and then left for loosed it. There is probably a better hex key/socket combo to use but hey it worked.
Filling it up though - I think it takes 3.5 l from a 5 l jug but don't quote me on this - so look online for correct amount to put in.
'87 Komet hightop DG