3.42 Posi or limited slip?

[Pureiron]

My truck will spin both tires on wet pavement. I thought I was crazy, cuz the dealer said that it had an open differential according to the vin#. So I had my wife go outside, in the rain(God bless her) and watch. Both tires do spin. What do I have under my truck? Dealer also said it was a 3.42

[shorepatrol2]

check codes in glove box , if there's a G80 , you have posi or limited slip

[Pureiron]

left that out. My friend told me to do that. I do not have that....is it possible someone went in and changed it? I am almost ready to crack the chunk open and take a look.