You'll get a tracking number, if you're lucky it might even be a real one, however, it won't be to your address or it will be for somethiing completely different, if you don't raise a case with eBay the instant you realise you've been ripped off (any time now) then the seller will mess you around, even offer to replace it as long as you ship the 'wrong' part back at some exorbitant cost to dealy the inveitabel sound of your money vanishing forever into their pocket or just ghost you completely.
As long as you don't give an inch you'll get your money back but be damn sure to follow the eBay process, even call eBay (yes they have helpful people on the end of the phones) and then your money is fairly safe.