Both, timing belt from cam to diesel pump. Timing chain from cam to crankshaft.
The 2013 Ford Fusion has double overhead cam (DOHC).
The 2012 Ford Fusion has double overhead cam (DOHC).
The 2014 Ford Fusion has double overhead cam (DOHC).
The 2010 Ford Fusion has double overhead cam (DOHC).
The 2006 Ford Fusion has double overhead cam (DOHC).
The 2011 Ford Fusion has double overhead cam (DOHC).
The 2009 Ford Fusion has double overhead cam (DOHC).
The 2007 Ford Fusion has double overhead cam (DOHC).
The 2008 Ford Fusion has double overhead cam (DOHC).
Cam Belt
The 2013 Ford Fusion-Energi has double overhead cam (DOHC).