360 magnum, need intermediate shaft

I'm looking for an intermediate shaft for a 360 magnum. Apparently they are hard to find. I believe the part number is Melling IS-72. I had my engine built, got it in, went to pump up the oil and noticed there was no intermediate shaft (well at least I didn't have to remove it...). I called the builder, he said they are a hard to find item (I wish he had told me that months ago that I needed to buy one).

Anyone have one?

Brian