I've experienced exactly one u-joint failure in my lifetime.  My buddy's '95 Lighting kept making this noise on take off and I told him likely it was a bad u-joint.  Of course I didn't know what I was talking about, until a month or two later he tried to pull out onto the highway and the rear u-joint let go.  Trashed the aluminum driveshaft too.

I think if you inspect the u-joints regularly the odds of one failing is pretty slim.  Safety loops are for racing, where cars running fast with 5,000 RPM clutch dump launches or coming off the line on a trans brake shock load the drivetrain to a degree never seen on the street.  I have seen u-joints fail at the strip and its is not pretty (catapults the car if its the front, etc.).  IIRC NHRA mandates a loop for cars running 13.99 or quicker, must be within 6" of the front u-joint, and must be a minimum of 1/4" thick x 2" wide or 7/8" x 0.065" wall tubing.  Mounting criteria is not specific.  I've run faster than that at the strip without one and never broken one, and the tech inspectors are pretty lax at my local track. 
 

Last edited by TKOPerformance (4/06/2024 6:01 AM)

I have one in my Lightning, but it's only because I was going to run it at the track with sticky tires every so often. On the street with street tires I really do not think it's necessary.

 

I wonder if the plate used for the convertible floor pans can be used as a safety loop?   I already added a heavy piece of bar stock to the front of it.

Although I also believe a driveshaft loop is likely unnecessary for a street car, if one installs one make sure that it is a 'loop' around the driveshaft.  You don't want that driveshaft coming up through the floor board.