Nope, that is definitely a (bone stock it appears) 4.6L modular. The intake is stock, and it certainly looks like a V8. And it's a modular (notice the overhead cams) ... a V6 up through 2004 is a pushrod motor.
Maybe someone wil remember this but a company named Dugan Mustang or Dugan Racing or something like that did the same thing a few years back. The company changed names but did and still does have a full page ad in the mustang mags. Their catalog was called "The Mustang Bible". I know some of you have heard of them.
Anyways when the new edge mustang came out they took a 94-98 mustang and put on all the newer sheetmetal, its the same car, just some different mounting points but for the most part the same. They had a larger collision & repair center so they had the expertise to do the conversion. Looked sweet and I think it was just something either a customer wanted or they did to promote their company. I don't think they showed this in their ads but there was some pics and write up in their catalog. I think their car was red though not silver.
Let me know if anyone has a clue what I am talking about, but I think that is what was done here.