Does the Viper need a driveshaft safety loop?
The belly tray of all Vipers should contain a broken drive shaft, and should EXCEED the requirements (and protection) offered by a safety strap. When the NHRA rule was written, there were probably no cars with a full under-tray like the Viper has. One exception is if you run an auxiliary fuel line down that shaft tunnel for some reason (ie turbos, S/C, etc....) you will want the redundant safety feature of a safety strap to contain the shaft even better.
Regardless of the rules, some say it is a good idea for the *half shaft* strap/loop. There has been several cases in the SoCal VCA with half shafts breaking and causing some serious problems. Especially when running slicks. The NHRA dictates that all sub-14 second cars should have a driveshaft loop. You can order the rulebook directly from NHRA, or if you subscribe to National Dragster, you get it for free. The loop is supposed to be on the transmission side of the driveshaft, to prevent cars from "pole vaulting". they make no assertions as to what you need to do with the differential side of the driveshaft. In a perfect world, everyone who responded with "you don't need this becuase of the Viperís undertray should be correct. However, many have experienced that when you go through the Technical Inspection at these NHRA tracks - you're kind of at the mercy of the Tech official. If they want to be a butthead, it's their prerogative. They may not think the Viperís undertray is well suited enough, or maybe they might want to adhere to the letter of NHRA law which requires a loop.
Itís surprising that the faster Viper owners don't get harassed by NHRA tech officials for other stuff as well. for instance, NHRA says you must have rollbar in sub 12 second cars (they need to see it and measure the diameter and thickness of the tube with their sonic testers - which must be within specs). further down it gets worse with seatbelts that must be replaced every 2 years, full cage, window nets, etc.