You won't damage the box, it is designed to turn under a lot of pressure and torque. (Feedback from the tires!) Just get a piece of leather or heavy fabric and put a pair of vise grips on the top shaft with the leather/fabric between the shaft and the vise grips. You won't need to put hardly any pressure on the shaft, it should rotate very easily.
5R08A, "298"(+.060, 6,000+ rpm), T-10, Crane XR-i, Disc (F), Dual Master, Heim Strut Rods - Spherical Bearing LCAs, Roller Perches, Arning Drop, 1" & 75" Anti-Sway Bars, Export & Monte Carlo, "functional" hood scoop, and GW Subframes.
Victory Red, Eagle Wheels, Power Antenna, White Int. w/ Black trim, Right & *Left* Indicators, Tach, Cruise, and a Glass Rear Window.