EATON, far better product and there rebuildable. I know the Auburns are now to but that because they wont handle the power. This is my opinion based on the one that was very short lived in my Nova. Was not a hole shot or even dumping the clutch. Just kicked in in the A-- from a 10 MPH roll and blew the cones and everything else out the housing cover. At that time I was not even pushing 400 HP. Was this just a bad unit, they said no, Said it must of be some kind of side force that caused the cones to disapear out the rear housing. Also took out my brand new 3.73 Richmond ring and pinion. I had the Eaton in the car for 3.5 years now and never a hint of a problem.
Ive ran an Auburn for 6 years. It has not Broke BUT it was only "POSI" for about 3 weeks. they would not Warantee it so Ive been stuck with it.
Ive been working on installing an eaton for the past week.
The auburn cone diffy is a fine unit. Works very well. The draw back is, it can not be rebuilt like the eaton unit. Other than the fact it can't be rebuilt, it is my experiance the auburn unit out-performs the eaton unit as far as driving both rear wheels. It's kind of cool how it works, it eats itself for you. The harder you push it, the more it fights back; so to speak. It will keep doing this untill it's ribs are shiny. Then you have to throw it out and replace it. I found that you can extend the life of an auburn simply by servicing the diffy fluid on a regular basis.
The eaton unit is the hot rodders rear in that it can be set up/changed for various applications. You can vary the spring pressure and dial it in. For a road racer this eaton rear, with it's multy disc/clutch and spring rate feature can be a tuners delight.
Either diffy will wear out eventualy, one can be rebuilt and the other is a throw away. One uses clutch discs and friction and requires a special additive. The other uses hydraulic stiction (like syncros). Like stated earlier, static spring rate is constant. Hydraulic pressure is exponential. You can overcome the spring rate with excesive force, it will 'give up' at some point. With hydraulics, the more you push it, the more it fights back. Something else will break.