[MikeK]

I don't see the engine placement as the problem. The torque tube with your OD pivots at the rear U-joint as the differential goes up/down over bumps. Too much upward differential travel may be the problem. Do you have rear shocks, and are they adjusted properly? Do you have the correct rear spring? Does your car sit at stock height or is it low? Plan D: Avoid 'serious' bumps.