Hi [NAME],   As Shine said, WS 2016 version is not tested with PE T350 at our labs, hence we cannot confirm the reliability of the server after installing WS 2016.   Please refer to the below link for any driver/ firmware download after purchasing your PE T350 server. [URL]
I'm getting a new T350 server, but I'd prefer to run WS 2016.  I have no problem doing the OS installation, but will I need to manually install any chipset, USB or any other drivers???  I assume I can find any drivers I need somewhere around the Dell site (I've never purchased a machine from Dell before). Thanks!    
New T350 downgrading to WS 2016