firewall
5 - 10
4 - 9
3 - 8
2 - 7
1 - 6
front
In the oil pan
68" wide
The biggest concern here is the alternator/voltage regulator design. The 68 is external while the 78 has it built into the alternator. There are websites that explain how to do this. The only other real issue is the coil. The HEI needs more voltage than the small wire running to the external type coil of a 68.
The height of the 2011 Ford Flex is 5 ft. 8 in. (68 in.).
The height of the 2009 Ford Flex is 5 ft. 8 in. (68 in.).
The height of the 2012 Ford Flex is 5 ft. 8 in. (68 in.).
The height of the 2014 Ford Flex is 5 ft. 8 in. (68 in.).
The height of the 2008 Ford Escape is 5 ft. 8 in. (68 in.).
The height of the 2010 Ford Flex is 5 ft. 8 in. (68 in.).
The height of the 2013 Ford Flex is 5 ft. 8 in. (68 in.).
.035 inch
I downloaded my owners manual at Ford Motor Company free of charge.