Wheelspin in turns

[marksawatsky]

I have a scratch built autocross car and when I'm turning and accelerating at the same time, it spins the inside rear tire. I have tried an Eaton TrueTrac (Torsen style) and now run a Variloc (clutch style) diff but they both spin the tire. The balance of the car is amazing and I have to be careful I don't make it understeery. I have SLA suspension in front and live axle with 3 link and Panhard out back. I wonder if longer travel shocks out back might keep tires planted. Any suggestions on how to solve this problem? Pictures of the car