323 or 327

The 5.3, which is it? I've heard everything from 323 to 327. I know they used to have a 327, but that was along time ago right?

it is a 323 according to the Wix filter book, and numerous other books I've looked up parts in.

GM lists it at 325 cu inches - http://media.gm.com/us/powertrain/en/product_services/Spec%20Sheets/Gen%20III/2006%20GenIII%20V8%20Truck%20(LM7,L59).pdf

//2000CAYukon

I would go off with what GM says it is, which is the 325ci