The ad says he will pay 500, but if he has a Tiger with a Ford 9" or nothing at all I'd bet 1000 is more like a good ballpark.
Have the serial number? look in a BON and see how many cars have that number.
If it has a posi core add a couple hun , 2.88 stock or a more desirable ratio? Hard to find a person who needs one , not cheap to ship either.
What is one worth? Are many people looking for one?
FYI All: I've had very good luck shipping larger items with Fastenall. Trannys, blocks, rears, etc. strapped to a small pallet and they cart them from store to store thru their National network. Very reasonable, no affill.