Well, as you can see the evidence below, it's definitely a Chevy Silverado.
EDIT: Not the case...see below.
Point of fact, is that F-2 is right, vehicle size does not matter.
Silverado: Note the wheel
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F-150: Dash not similar, nor the seat (and sorry, no side view was available to compare)
RH77
EDIT: Correction: I think it's a previous-gen F-150, but the wheel throws things off. GM dashes aren't as swoopy, and the 2-tone paint is signature F-150.