In the VLSD. There is no clutch pack/disks in it. It's a sealed unit inside the carrier. Inside that is silicone fluid that is non-replaceable. Don't need a LSD additive either. a lot of people here use 75w-90 synthetic unless you have an OS Giken. Then you have to use their lube which is 80w-250.
DO NOT use GL-5 lube in the tranny. It eats the synchronizers. Use GL-4
https://www.widman.biz/uploads/Transaxle_oil.pdf