[Bob Putnam]

Worth a try (from our manual):

Differential: Fill with Moroso climbing gear lube, SAE 90, part number 34800, mixed with 4 to 8 oz. of Amalie limited slip additive (part # 505-6775). If the above are not available, you may use 80W-90 GL5 lubricant with an equivalent limited slip additive.

If the limited slip seems to be sticking (ratcheting around sharp corners), drain and refill, replacing the Amalie additive with 2 tubes of GM additive 1052358.