It is always a good idea to measure the companion flange on 8.8 rear ends to verify what pinion flange is needed. The critical dimensions are the bold circle and the center register, which aligns the flange. The U-joint size is also important to keep in mind. As I recall, the stock Cobra pinion flange use a 1330 u-joint, but I bet you can get a 1350 flange as well.
Andrew