I got a set of alum nemmy diffs for my genesis. I used a butane torch and my snap on 3/8 drive hex's to get the screws out to change fluid. Thing is, I couldn't get 2 screws out of one diff.... At all...
Everything else went just fine, but theses 2 screws stripped to shreds. I gave up and just put the diff in with the stock fluid, but with enough patience and enough heat, it should be possible