Where to get the correct 360 oil pan.

It sure says 360 on the side of the block.It was the original engine in the van and the documentation with the van said it was a 5.9.From what others have said the 360 has the larger rear main,as I have.That would make a 273/318/340 the smaller main,thereby causing the current situation I have before me.The small rear of the new pan will not fit over the larger main of the 360 that I have. :glasses6: