A loop is only needed if the tailshaft uses universal joints. So if it uses a cv joint no loop is needed. If a uni joint is used a loop needs to be fitted less than 6 inches from the center line of the uni joint. Most of the driveline protection section of the rules refer to rwd vehicles only.

Fitt the battery isolator to the earth side of the battery as said. How quick is the car?

Cheers

Brett