Why hasn't anyone released a HD truck with a Turbo V8?

It seems that every vehicle manufacture is making their HD trucks more and more capable. With the introduction of turbo charged V6 engines like the Ecoboost, Why hasn't anyone released a 6.2\6.4 turbo charged v8 Gas engine?

The only reason I can think of is that it would possibly reduce the number of Diesel engines they sell.