I can't locate 6.5 IFC right now, but I don't know which OS you are on. It should be available though Graphisoft's website as a download. If not, email your reseller.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"