Yo Rick,
A while back I asked Mike Bontoft of CWI about this. His advice was two bottles of the GM limited slip additive in addition to the usual gear
oil.
Mike used to sell a British-made additive but apparently he couldn't get it when I needed it, and maybe not at all since.
If you need more info I can probably do some archaeology and get you some specifics as to what I used.
Mike was not receptive to Redline as I recall.
Regards,
Tom