I love him!! Big and stocky and sweet.
Just judging from his appearance, my 2 top guesses would be either Mustang or some sort of draft cross. If he is a mustang though, he would have had to be born after his mother was adopted or else he would have been branded.
He sure reminds me of my former mustang boy, big feet and all. Koda only stood about 14.2 and wore a size 2 shoe.