10/11 speed freehub compatibility I have a Sram 10 speed cassette and I'm looking to upgrade to Shimano XT M8000 1x11. I wanted to know if I can use the same freehub body or if I need to get a new one. 

Thank you for your help.
Yes, it will work fine. For road cassettes, the freehub body length had to be increased for 11 to fit more cogs, but for mountain there was no such change because the largest cog slightly overhangs the hub flange.