what vehicle was the front D44 out of that came in your truck? you being the third owner, how can you 100% say it was factory? "that easily may have been a special order" makes me believe you don't have proof, just someones word.
also, a dana 60 was not a factory option. like don said, the dealer could have installed one for a person (although i HIGHLY doubt they did).
where are the pics?