I purchased a 2016 regular
I purchased a 2016 regular cab short box XLT with the base 3.5 l. motor. So far excellent fuel economy (20 mpg) and very good motor response. Much more power than my 3.0 l. Ranger. The 3.5 base shares many mechanical internal parts with the eco-boost so this is why I think that Ford went with the 3.5 over the 3.7. Not sure, but I think the same transmission too.