When the car manufacturers build their cars they always try to save as much money as they can to make more of a profit. For example, if a car maker can save a dollar per unit by switching tires, we're talking about potentially millions of dollars in total savings for the company. This same mentality is used by most car makers when it comes time for their rearends. Why spend money on a posi-traction rearend when a limited slip would do pretty much the same job without incurring the expense?
Performance enthusiasts know, however, that a posi-traction rearend is positively the way to go, so we called up Sutton Engineering in La Puente, California, where they specialize in shortening rearend housings as well as building stock and race setup rearends. The Sutton Engineering team had just finished adding a posi-traction setup on a chrome rearend for a lowrider and they invited us to document the next one that they were working on as the steps are fairly the same on most GM third members. We packed our cameras and were on our way to document the pros at Sutton Engineering as they added posi-traction gears to a factory stock rearend for better handling and performance.