Can anyone tell me where I can find a build code that will tell me if i have a LS rear in my truck? I recently watched a video of my truck taking off hard and once under boost the left rear spun a little bit (equal traction maybe...). I'm wondering if I have a worn out LS unit. Maybe some fresh additive will help get both spinning again.

 

There are two ways. Take your vin # and call the dealer. With it, they can reference the "build sheet" of your truck. It has all the info you need. Or take the numbers off the tag on the diff cover. Call a driveline shop and they can tell you what you need to know
Take the truck and put one wheel in dirt, the other on pavement. Nail it. What happens?