My truck has a 14-bolt rear differential. I've removed the cover and drained the oil, and am about ready to button it all back up and refill with fresh oil. However, I can't figure out if this truck has an LSD or not, and therefore whether to add LSD additive into the oil.
Picture:
https://imgur.com/VLqjWER
With the rear end jacked up, and transmission in neutral, when I spin one wheel, the other stays stationary. But if I put in gear and spin one wheel, the other spins the other way.
I'm inclined to think this means it does NOT have an LSD, but I'm getting so much conflicting information after searching extensively that I am not feeling very confident about this. Help?