What engine does my 2004 chevy silverado have?

So i got this truck recently and was wondering what engine it had. It has "vortec max" badging on the doors and it says "z71" on the bed. I looked this up and it should have a 6 liter v8. But when i looked up the vin and the 8th digit is a T, which means it has a 5.3l v8. soo my question is, is there any way to know for sure what engine it has, by looking under the hood? I noted it had a plastic cover with vortec on it, what looks like an aftermarket cold air intake, the numbers 706 on the passenger side cylinder head next to the oil filler, and that it was at least a v8. It is an extended cab, black with 20 inch chrome rims.