Fuel Pump on crown vic '11

Hi, guys!
I've got a question.
Does anyone know is it possible to replace only a fuel pump in 2011 model fuel pump assembly or it should be changed with the whole assembly that cost $300-up?
Ive tried to find just a fuel pump, but there is only one I can get on ebay and its Airtex E2158(which is not good at all). It says FOR 2003-11 FORD CROWN VICTORIA -GRAND MARQUIS AND LINCOLN TOWN CAR 4.6, but the official website of Airtex doesn't give that pump number(E215, and gives only the whole assembly part. And that makes me confused.
So maybe someone knows something about it.

Thanks.

This is just my two cents but every time I do just the pump it fails within a year and I have to do the whole assembly.

Did you check rockauto.com for prices? Looks like they have the whole lifetime warranty Airtex for 170.