Easiest way to know is jack up the rear end, both tires in the air. Put the truck in neutral, spin one tire and see which direction the other tire goes. If it turns the same way as the tire you spin it is a LSD if it turns the opposite way it is an Open Diff. It takes 2mins. It takes more time to read the build sheet.

 

^thanks for the tip, future use possibly

 

You dont have lsd just looked at our ram build sheet and it lists anti spin diff This is what ours lists
3.92 Axle Ratio
Corporate 9.25 LD Rear Axle
Anti-Spin Differential Rear Axle