On the gear oil fill/differential side (as opposed to the clutch pack atf fluid side- I changed that no problem). I've tried everything including penetrating oil. The problem is the gap between the bolt and [I dont remember exactly now, part of the suspension or the shaft going from the diff to the wheel] is such a short space that I cant get a ratchet and socket in there. The bolt was a tad stripped when I started to try to wrench it loose, and now it's even more stripped. I'm working the bolt so hard that the whole ayc is shaking, which makes me nervous. It hasnt budged one millimeter. Aside from bringing it to the dealership, what can I do?

Secondly, I see what looks like another fill bolt facing the rear of the car. I havent seen anything online or in the service manual mentioning this bolt. It's labelled just like the front-facing one, gear oil, arrow pointing towards it, but it's a different size. Is this indeed a secondary fill bolt? Mediocre pic attached. At least I can finish my drivetrain fluid changes myself before figuring out what to do with this stupid stuck bolt.

 

Diff LSD Diaqueen oil fill plug is facing the driveshaft.

SAYC Diamond ATF oil fill plug is facing the back of the car.

 

I had that same secondary fill bolt location thing marked on mine, I never bothered to try it but it looks like it was just stamped wrong or something you can give it a try I guess but I wouldn't think it would work.

 

I do know where these two plugs are. This is an additional plug, not noted anywhere in the service manual or that I've found online.

 

Yeah it looks odd. The bolt is a different size, and there's a sort of metal bracket connected to that part of the diff underneath the bolt. Implying the bolt is there to hold that end of the bracket in place- not a gear oil fill spot. Darn, oh well

 

I would find someone that can just weld another nut or something on the end of the one that's there or use some heat to help break it loose, I wouldn't advise drilling or anything since you know metal shards plus little gears is never a good combo. Also of course order a new plug as well.