I had the same type problem with mine, It spins both straight on the street, but anything sideways around a corner it likes to spin just one. It was under warranty so I took it it, they replaced the entire diff, axle housing as an entire assembly, it still does the exact same things it did before. Im convinced its the type of limited slip this rear end uses and personally i think it sucks, The auburn type posi in my 94 firebird worked flawlessly all the time, always two wheels, i could do donuts all day in the that car, wet or dry.
06 GTO IBM 408 Stroker-Sold
06 Corvette, Supercharged 607whp, RPM trans and Diff, RPS twin disc, Z06 susp, Dewitts Rad, Custom Fuel system