Replaced differential with used one year ago. Lots of oil all over driveway now

I dont know. Went out to car and all the...guessing it was oil, dark was ALL OVER the driveway. Battery had died and I was afraid to charge batter because all this gunk was all over the concrete. As days went by more and MORE was all over. Where ever it came from im sure its empty where ever it came from Now they did mention I had gaskets to be replaced costing about three or four hundred dolars. Didnt have money to fix at that time. Van just sits there now. Some mechanics dont want me to spend anymore money on the van. But I love my van! Cant afford another car