There is a sticker in the glove box that will say LD or LSD on it. There's lots of threads on it that have come up recently try a search for them I also made a thread the other day on getting a build sheet for your truck through dodge that will tell you everything about it it should be within the last two pages on here.

 

build sheet thread link https://dodgeforum.com/forum/2nd-gen-dakota-tech/179153-emissions-question.html