How to Tell If a Chevy Truck Has Positractionby Dale Yalanovsky
Both rear wheels of a Chevy truck with positraction (also called limited slip) will rotate when the truck is in gear. This means that there will be greater traction in all environments, as both rear wheels are turning under power. Most heavy-duty Chevy trucks come standard with positraction rear ends, but light-duty trucks may not have this feature. There is way that you can tell.
Park your truck on a level space, preferably concrete or asphalt. Chock the front wheels using manufactured wheel chocks if possible, and otherwise alternatives such as bricks or logs.
Jack up both sides of the rear of your Chevy truck and place jack stands beneath the frame to hold the rear wheels safely off the ground.
Shift your transmission into neutral so that the rear wheels rotate freely.
Grasp one rear wheel, turn it and observe the other rear wheel. If the other rear wheel turns in the same direction, there is positraction. Otherwise there is not.