theres isnt one just for chevy. chevy has a wide range of customers much like jeep. from the young kid thats into getting stuck in 10 foot deep mud to a old man pulling a cattle trailer on his ranch that loves chrome.
the real question is what does he want out of the truck? if he wants diesel power then i say buy a duramax or 8.1 vortec. i cant say what to look for if i dont know what hes looking to get out of it.