Driveshaft loop location.

It says 6" max behind the front u-joint.
The further back the loop is placed, the more dangerous the front part becomes. The back end whipping around is behind you and the driveshaft will want to exit towards the back. The front part whipping around is usually right next to you and is most important to "contain". Moving it forward, to less than 6", is safer. There is less room for the tube to bend at the front, especially when the front joint breaks and the rear is still attached while going down the track.