The reason S-10 rear C/V's fail is two main reasons.
1. The rear leaf springs begin to sag this causes the pinion to rotate up-wards which in turn causes the grease in the C/V to run away from the ball and seat  causing it to burnout.
2. 3R C/V's have a heavy spring load in the kit, this causes the C/V to run hot in the first place.  When the rear leaf springs begin to sag this creates a greater angle for the C/V to rotate through.  Combine this with the heavy spring load in the C/V and the kit runs to hot and burns the grease up and the C/V kit fails.
 

These problems can now be solved by using a newly designed kit that replaces the 3R kit.  This new C/V kit uses a 1330 C/V kit with a custom designed 5/8" ball stud that presses on the 3R stud in place of the ball.  This new kit seals better at increased angles and holds more grease, it also runs cooler due to the reduced spring load in the kit.  There are no modifications to the ball stud or H-yoke.  The new C/V kit is easy to service, using a 1330 centering kit and seal with a replaceable ball stud.  This kit is based on a Lincolns C/V and look at how long they last.