Do I have a 5.3 Gen IV?

[Oilbrnr]

So I got this engine in a trade back in '08. It was supposed to be out of an Escalade which would have made it a 6.2, which it isn't.

The iron block clearly has the 5.3 and 4.8 Gen IV casting on the right sides front and rear with a BLUE paint dot on the 4.8. Seeing this, combine with the 243 casting heads, I assumed it was in fact a 4.8, however now that I'm closer to doing the swap to my K5 I've discovered on closer examination a couple of items that have me wondering if it might actually in fact be a 5.3.

First, it has 12594512 flex fuel injectors, second it has VLOM or a Valve Lifter Oil Manifold for Active Fuel Management. It does NOT have the VVT solenoid on the cam cover. All of this (other than the 243 heads) point to a LMG 5.3. Oh, and it does have the E38 ECM. From what I can find so far online, neither flex fuel or DoD was offered on the '07 4.8

I wanted to ask here first before I post on ls1tech, as they seem to be somewhat of a hostile group to noobs, which is kinda irritating. Is it possible to see the shape of the piston with the plug out, or feel it with a pencil for example?

Thanks for any help.