Four men one dream job. That’s the situation for a quartet of wannabe Texans running backs – three undrafted rookies plus a veteran – who are vying for the No. 3 spot on the roster behind Arian Foster and Ben Tate. Dennis Johnson from Arkansas Cierre Wood from Notre Dame and Ray Graham from Pitt as well as fourth-year pro Deji Karim who has played for the Jaguars and the Colts are all expected to see action against the Vikings when the Texans open their preseason Friday night. Johnson the likely starter with both Foster and Tate injured has been the most impressive in training camp – this after not even being invited to the NFL’s draft combine in Indianapolis in February. He signed with Texans in large part because of Foster’s back story. He too went undrafted.