Opening ours up is pretty much impossible unless you make the "key" that fits in these 6 slots around the inside of the perimeter.
And if you look closely you'll note where you can see that the locking ball bearing has been drilled out.
Absolutely nothing like the m3 diff.. whitch has like 6 bolts, undo and take apart, easy peasy..
Lol yeah that video shows the m3 casing, completely different to ours. If I drop back into the shop, I'll take a picture of the "key" since I payed for him to make it. Lol. Or you could contact Sava in Dubai and ask him. Nice bloke, smokes a lot..
We cracked open the case with the "key" with a 4 meter extension bar and 4 big guys on it... It's not an easy job, that's for sure.
You'll need to order the specific z4m clutch pack kit, as after we opened mine up we discovered that the E46 has 2 clutches less than the z4m, which is why Racingdiffs.com now offer a specific pack for the z4m.
Hope that helps , explains a bit..
Oh and after cracking the diff, I decided to just put in a proper race diff from them. Lifetime Warrenty.. gotta love that.. 30/60 ramps. Got it at a pretty darn good price, seeing as we were sharing info with Racingdiffs.com
(GearMasters Dubai, UAE)